DI-LR Strat
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How tough was the DI-LR on CAT 2017 Slot 1 ?

After doing two posts on Slot 2 of CAT 2017, I kind of felt in the groove to take a shot at Slot 1 as well. Was it really that tough? If one of my best friends and a beast far as cracking the CAT  is concerned did not attempt all questions as is usually the case — how many can a test-taker currently scoring around 90 percentile in the SimCATs realistically attempt? How should he or she have gone about analyzing the section, in what order should the sets have been attempted? I thought I will take up these questions in this blog post so that many fears can be laid to rest.


The Fast Food Joint Set

Healthy Bites is a fast food joint serving three items: burgers, fries and ice cream. It has two employees Anish and Bani who prepare the items ordered by the clients. Preparation time is 10 minutes for a burger and 2 minutes for an order of ice cream. An employee can prepare only one of these items at a time. The fries are prepared in an automatic fryer which can prepare up to 3 portions of fires at a time and takes 5 minutes irrespective of the number of portions. The fryer does not need an employee to constantly attend to it, and we can ignore the time taken by an employee to start and stop the fryer; thus, an employee can be engaged in preparing other items while the frying is on. However, fries cannot be prepared in anticipation of future orders.

Healthy Bites wishes to serve the orders as early as possible. The individual items in any order are served as and when ready; however, the order is considered to be completely served only when all the items of that order are served.

The table below gives the orders of three clients and the times at which they placed their orders.

Client No. Time Order
1 10:00 1 burger, 3 portions of fries, 1 order of ice cream
2 10:05 2 portions of fries, 1 order of ice cream
3 10:07 1 burger, 1 portion of fries

 

Assume that only one client’s order can be processed at any given point of time. So, Anish or Bani cannot start preparing a new order while a previous order is being prepared.

35. At what time is the order placed by Client 1 completely served?

  1. 10:17
  2. 10:10
  3. 10:15
  4. 10:20

36. Assume that only one client’s order can be processed at any given point of time. So, Anish or Bani cannot start preparing a new order while a previous order is being prepared.

At what time is the order placed by Client 3 completely served?

  1. 10:35
  2. 10:22
  3. 10:25
  4. 10:17

37. Suppose the employees are allowed to process multiple orders at a time, but the preference would be to finish orders of clients who placed their orders earlier.

At what time is the order placed by Client 2 completely served?

  1. 10:10
  2. 10:12
  3. 10:15
  4. 10:17

38. Suppose the employees are allowed to process multiple orders at a time, but the preference would be to finish orders of clients who placed their orders earlier.

Also assume that the fourth client came in only at 10:35. Between 10:00 and 10:30, for how many minutes is exactly one of the employees idle?

  1. 7
  2. 10
  3. 15
  4. 23

If we look at this set through the Standard- Plugin-Closed lens then what do we see?

It can be termed a non-standard set since sets around the cooking of food have never appeared on the CAT! But maybe given our current, insane obsession with food and food shows, the CAT test-setters didn’t want to feel out of step with the times.

But we have seen scheduling sets before so it is not that unique a set.

The conditions are fairly simple and require no deduction.

While there is additional information given in the set, it is not something that makes the set an open set.

I would rate this set and 9 out of 10 and do it straight away. Since it seems so simple, I’ll just be a tad careful to not overlook anything.

Question 1: Client 1 is fully served by 10:10 since the longest time to cook is taken by the burger, 10 minutes.

Question 2: Since 2 orders cannot be prepared simultaneously, the prep for Client 2 can only start after Client 1 gets done at 10:10 and then Client 2’s order is taken up, which gets over with the fries taking the longest time at 10:15, after which Client 3’s order is started and finished off by 10:25 since the longest time is taken for the burger.

This is basically 6 marks in about 5 minutes including the reading of the set.

The rest of the two questions just remove the serial processing conditions, orders can be processed simultaneously.

Question 3: Of the two workers making Client 1’s order, one gets free by 10:02 as soon as the ice-cream is done. This worker can take up Client 2’s order as soon as it arrives at 10:05 and can serve it by 10:10 since the longest time taken is by the fries.

Question 4: Continuing from the previous question, once Client 2 gets started at 10:05, the worker making the ice-cream gets free at 10:07 and can take up the order of Client 3 and serve it by 10:17. So this worker was free for 3 minutes from 10:02 to 10:05 (between orders 1 and 2) and the first worker who finishes the burger for the Client 1 at 10:10 is free from then onwards. For how long was one of them free? From 10:17 both of them are free. Before that Worker 1 is free from 10:10 to 10:17 while the other worker is free for 3 minutes, making the total 10 minutes.

The only weird thing about this set is the irony in the name of the fast food joint — Healthy Bites — selling burgers, fries, and ice-cream!

But for test-takers, this is a super healthy set with 12 marks in 10 minutes very much on the cards.


The Education Survey Set

A study to look at the early teaming of rural kids was carried out in a number of villages spanning three states, chosen from the North East (NE), the West (W) and the South (S). 50 four-year-old kids each were sampled from each of the 150 villages from NE, 250 villages from W arid 200 villages from S. It was found that of the 30000 surveyed feds 55% studied in primary schools run by government (G), 37% in private schools (P) while the remaining 8% did not go to school (O).

The kids surveyed were further divided into two groups based on whether their mothers dropped out of school before completing primary education or not. The table below gives the number of kids in different types of schools for mothers who dropped out- of school before completing primary education:

It is also known that:

  1. In S, 60% of the surveyed kids were from G. Moreover, in S, all surveyed kids whose mothers had completed primary education were in school.
  2. In NE, among the O kids, 50% had mothers who had dropped out before completing primary education.
  3. The number of kids in G in NE was the same as the number of kids in G in W.

Screen Shot 2018-10-31 at 6.23.49 PM.png

39. What percentage of kids from S were studying in P?

  1. 37%
  2. 6%
  3. 79%
  4. 56%

40. Among the kids in W whose mothers had completed primary education, how many were not in school?

  1. 300
  2. 1200
  3. 1050
  4. 1500

41. In a follow-up survey of the same kids two years later, it was found that all the kids were now in school. Of the kids who were not in school earlier, in one region, 25% were in G now, whereas the rest were enrolled in P; in the second region, all such kids were in G now; while in the third region, 50% of such kids had now joined G while the rest had joined P. As a result, in all three regions put together, 50% of the kids who were earlier out of school had joined G. It was also seen that no surveyed kid had changed schools.

What number of the surveyed kids now were in G in W?

  1. 6000
  2. 5250
  3. 6750
  4. 6300

42. In a follow-up survey of the same kids two years later, it was found that all the kids were now in school. Of the kids who were not in school earlier, in one region, 25% were in G now, whereas the rest were enrolled in P; in the second region, all such kids were in G now; while in the third region, 50% of such kids had now joined G while the rest had joined P. As a result, in all three regions put together, 50% of the kids who were earlier out of school had joined G. It was also seen that no surveyed kid had changed schools.

What percentage of the surveyed kids in S, whose mothers had dropped out before completing primary education, were in G now?

  1. 94.7%
  2. 89.5%
  3. 93.4%
  4. Cannot be determined from the given information

Have you really decoded this set on first reading?

After the relatively easy first set that didn’t demand too much concentration to understand the set or to solve the questions, this set raises the level on both counts.

In the previous post, we discussed how sets that are tough require you to not be on autopilot mode while reading and while solving.

Data Interpretation before Data Crunching

What I like about this set is that it tests your ability to look at data given and draw inferences about the data missing at a top-level, rows and columns missing, not data missing in cells given in the table.

The key thing is to understand what the table gives you.

You have the total number of kids in NE, W & S. So you have the totals of the rows.

The table gives you data pertaining to kids whose mothers whose dropped out of school.

The missing data pertains to kids whose mothers went to school.

So next to each column G, P and O there is a missing column with the numbers of the kids whose mothers went to school.

So each of the columns G, P and O has two sub-columns, of which one is filled and the other is missing.

The set also gives you the totals of G, P, and O.

The questions will revolve around the missing values that can be inferred from the three conditions.

Are the conditions plugin or deductive, they are plugin conditions since they give you further numbers that can be fit into the table.

Is the set a closed one? Yes, since the questions are directly asking for the values.

The set is standard, plugin and closed.

The last two questions are based on common additional information hence solving one means solving the other as well.

I would rate this a 7 out of 10.

This is not different from the Pizza Set in Slot 2, where TC and NC were given in the Table but the missing columns were DD and EC. In both sets, the complementary information was missing — if it’s not TC-NC then it has to be TC-EC, if it’s not S-G-Dropout then it’s S-G-School.

Since the reading and interpretation would have taken time. I think 12 marks in 15 minutes is not a bad return from this set.

Let us see how the set is solved. And is there a bit of Math-LR involved? Yes, in the last two questions.

If you rushed through the reading without visualizing the missing data, you will have had a tough time.


The Entrance Test Set

Applicants for the doctoral programmes of Ambi Institute of Engineering (AIE) and Bambi Institute of Engineering (BIE) have to appear for a Common Entrance Test (CET). The test has three sections: Physics (P), Chemistry (C), and Maths (M). Among those appearing for CET, those at or above the 80th percentile in at least two sections, and at or above the 90th percentile overall, are selected for Advanced Entrance Test (AET) conducted by AIE. AET is used by AIE for final selection.

For the 200 candidates who are at or above the 90th percentile overall based on CET, the following are known about their performance in CET:

  1. No one is below the 80th percentile in all 3 sections.
  2. 150 are at or above the 80th percentile in exactly two sections.
  3. The number of candidates at or above the 80th percentile only in P is the same as the number of candidates at or above the 80th percentile only in C. The same is the number of candidates at or above the 80th percentile only in M.
  4. The number of candidates below the 80th percentile in P: Number of candidates below the 80th percentile in C: Number of candidates below the 80th percentile in M = 4:2:1.

BIE uses a different process for selection. If any candidate is appearing in the AET by AIE, BIE considers their AET score for final selection provided the candidate is at or above the 80th percentile in P. Any other candidate at or above the 80th percentile in P in CET, but who is not eligible for the AET, is required to appear in a separate test to be conducted by BIE for being considered for final selection. Altogether, there are 400 candidates this year who are at or above the 80th percentile in P.

43. What best can be concluded about the number of candidates sitting for the separate test for BIE who were at or above the 90th percentile overall in CET?

  1. 3 or 10
  2. 10
  3. 5
  4. 7 or 10

44. If the number of candidates who are at or above the 90th percentile overall and also at or above the 80th percentile in all three sections in CET is actually a multiple of 5, what is the number of candidates who are at or above the 90th percentile overall and at or above the 80th percentile in both P and M in CET?

Enter your response as an integer using the virtual keyboard.

45. If the number of candidates who are at or above the 90th percentile overall and also at or above the 80th percentile in all three sections in CET is actually a multiple of 5, then how many candidates were shortlisted for the AET for AIE?

Enter your response as an integer using the virtual keyboard.

46. If the number of candidates who are at or above the 90th percentile overall and also are at or above the 80th percentile in P in CET, is more than 100, how many candidates had to sit for the separate test for BIE?

  1. 299
  2. 310
  3. 321
  4. 330

On the face of it, the set seems standard but is it?

How many times have you seen  Percentiles and Venn Diagrams together?

The conditions are partly plugin and partly deductive. In addition, there is another set of selection criteria given.

If you look at the questions and options you can see that it is an Open Set. The options for the first question suggest more than one possibility.

There is common additional information for 2 and 3 and a different one for 4.

This would be a Non-standard, Partly Plugin and Open.

Given the complexity, I would rate it a 6 out of 10 and move on to the next set.


The Happiness Index

Simple Happiness index (SHI) of a country is computed on the basis of three parameters: social support (S), freedom to life choices (F) and corruption perception (C). Each of these three parameters is measured on a scale of 0 to 8 (integers only). A country is then categorized based on the total score obtained by summing the scores of all the three parameters, as shown in the following table:

Total Score              0-4                        5-8                    9-13               14-19                      20-24

Category         Very Unhappy       Unhappy            Neutral          Happy               Very Happy

Following diagram depicts the frequency distribution of the scores in S, F, and C of 10 countries – Amda, Benga, Calla, Delma, Eppa, Varsa, Wanna, Xanda, Yanga, and Zoorna:

Screen Shot 2018-10-31 at 4.44.17 PM.png

Further, the following are known.

  1. Amda and Calls jointly have the lowest total score, 7, with identical scores in all the three parameters.
  2. Zooma has a total score of 17.
  3. All the 3 countries, which are categorized as happy, have the highest score in exactly one parameter.

47.What is Amda’s score in F?

Enter your response as an integer using the virtual keyboard.

48. What is Zooma’s score in S? 

Enter your response as an integer using the virtual keyboard.

49. Benga and Delma, two countries categorized as happy, are tied with the same total score. What is the maximum score they can have?

  1. 14
  2. 15
  3. 16
  4. 17

50. If Benga scores 16 and Delma scores 15, then what is the maximum number of countries with a score of 13?

  1. 0
  2. 1
  3. 2
  4. 3

Since it is a bar-graph it is fairly standard in terms of information.

The conditions are all deductive since you have to consider the implications of the numbers.

Also by now, you will have realized that this is a Math LR set.

  • How can you get a total of 7 with 3 scores?
  • How can I get a total of 17 with 3 scores?

Two of the questions are closed and two are open.

Standard, Deductive (Math-LR), Partly open.

I will rate this a 6 out of 10.

You can check out the solution here.


The Projects Set

There are 21 employees working in a division, out of whom 10 are special-skilled employees (SE) and the remaining are regular- skilled employees (RE). During the next five months, the division has to complete five projects every month. Out of the 25 projects, 5 projects are “challenging”, while the remaining ones are “standard”. Each of the challenging projects has to be completed in different months. Every month, five teams – T1, T2, T3, T4 and T5, work on one project each. T1, T2, T3, T4 and T5 are allotted the challenging project in the first, second, third, fourth and fifth month, respectively. The team assigned the challenging project has one more employee than the rest.

In the first month, T1 has one more SE than T2, T2 has one more SE than T3, T3 has one more SE than T4, and T4 has one more SE than T5. Between two successive months, the composition of the teams changes as follows:

a. The team allotted the challenging project, gets two SE from the team which was allotted the challenging project in the previous month. In exchange, one RE is shifted from the former team to the latter team.
b. After the above exchange, if T1 has any SE and T5 has any RE, then one SE is shifted from T1 to T5, and one RE is shifted from T 5 to T1. Also, if T2 has any SE and T4 has any RE, then one SE is shifted from T2 to T4, and one RE is shifted from T 4 to T2.

Each standard project has a total of 100 credit points, while each challenging project has 200 credit points. The credit points are equally shared between the employees included in that team.

51. The number of times in which the composition of team T 2 and the number of times in which the composition of team T 4 remained unchanged in two successive months are:

  1. (2, 1)
  2. (1, 0)
  3. (0, 0)
  4. (1, 1)

52. The number of SE in T1 and T5 for the projects in the third month are, respectively:

  1. (0, 2)
  2. (0, 3)
  3. (1, 2)
  4. (1, 3)

53. Which of the following CANNOT be the total credit points earned by any employee from the projects?

  1. 140
  2. 150
  3. 170
  4. 200

54. One of the employees named Aneek scored 185 points. Which of the following CANNOT be true?

  1. Aneek worked only in teams T1, T2, T3, and T4
  2. Aneek worked only in teams T1, T2, T4, and T5
  3. Aneek worked only in teams T2, T3, T4, and T5
  4. Aneek worked only in teams T1, T3, T4, and T5

On the face of it, this is a kind of set that I don’t like since it needs more donkey work than reasoning but I know that I am halfway through the test and have got 24 marks by solving 2 out of 4 sets.

I know that I need another 2 out of the remaining 4 to safely clear the cut-off.

Is the set standard? No!

Conditions are neither plugin nor deductive but directions.

Is it a closed set? Yes, all the questions have direct answers and only 1 has additional information.

Non-standard, Directions, Closed.

I know that this set is about putting my head down, concentrating hard and making 5 tables for 5 months.

I will rate this a 7.5 out of 10.

I start with the first condition that each team has one SE more than the next one starting with T1.

What is the total number of SEs? 10.

Math-LR, anyone?

If the lowest one, T5 has x then the rest will x+1, x+2, x+3 and x+4.

5x + 6 = 10

But we have a problem since x cannot be a fraction.

Even if x=1 then 5x+6 will be more than 10.

What does that mean?

T5 has 0 SEs and the rest have 1 SE, 2 SEs, 3 SEs, and 4SEs, totaling up to 10.

The team with the challenging project has 1 more team-member than all the rest.

So if the total number is 20, all the rest are x,x,x,x, and the team with the challenging project is x+1. In other words, four teams with 4 people and the one team with the challenging project having 5 people.

So for Month 1 T1 has the challenging project and hence 5 people, 4 SE + 1 RE. The rest have 3 SE + 1 RE, 2 SE + 2 RE, 1 SE + 3RE and 0 SE + 4 RE.

After this, you just put your head down and do the donkey work of rotating people around the teams as per the directions and you will end up with a rough sheet that looks like this.

IMG_3571

I suggest doing this on your own to see how prone you are to making silly mistakes.

Questions 51 & 52: The first two questions are just about marking the answer from the table.

The next two are classic Math-LR.

Question 53: An engineer can get either get 40 points

  • by being part of a 5-member team on a challenging project that gets 200 points in total or

25 points

  • by being part of a 4-member team on a regular project that gets 100 points in total

So all the question is asking you to do is to see which number cannot be made with 40s and 25s.

The maximum is all 40s or 200 points. Any number less than that is a combination of 25s and 40.

So what will I do?

I’ll remove 40 or multiples of 40 from each option and see if the remainder is divisible by 25. Or I can remove 25 or multiples of 25 and see if the balance is divisible by 40.

Option 1, remove 40 from 140 and 100 is divisible by 25.

Option 2, remove 40, 80 or 120 from 150 but the remainder is not divisible by 25. Hence this is your answer.

Question 54: If Aneek scored 185 points then he should have scored four 40s and one 25. So he was one 4 challenging projects and one 1 regular project.

If every month starting with T1, the next team was given a challenging project then it means that Aneek moved on to the next team every month except for one month.

Now you go by options and see which one is not possible.

Option 4 is not possible since there is no direct exchange between T1 to T3. There is no way Aneek can go from T1 to T3 without going through T2.

This set will if done properly ensuring that you make no error will at the maximum take 15 minutes for 12 marks.

So we are around the 45-minute mark with 36 marks in hand.


The Platform Set

In a square layout of size 5m × 5m, 25 equal sized square platforms of different heights are built. The heights (in meters) of individual platforms are as shown below:

CAT 2017 DI-LR - The Platform Set

Individuals (all of the same height) are seated on these platforms. We say an individual A can reach art individual B if all the three following conditions are met:

  1. A and B are In the same row or column
  2. A is at a lower height than B
  3. If there is/are any individuals (s) between A and B, such individual(s) must be at a height lower than that of A.

Thus in the table given above, consider the Individual seated at height 8 on 3rd row and 2nd column. He can be reached by four individuals. He can be reached by the individual on his left at height 7, by the two individuals on his right at heights of 4 and 6 and by the individual above at height 5.

Rows in the layout are numbered from top to bottom and columns are numbered from left to right.

56. How many individuals in this layout can be reached by just one individual?

  1. 3
  2. 5
  3. 7
  4. 8

57. Which of the following is true for any individual at a platform of height 1 m in this layout?

  1. They can be reached by all the individuals in their own row and column
  2. They can be reached by at least 4 individuals
  3. They can be reached by at least one individual
  4. They cannot be reached by anyone

57. We can find two individuals who cannot be reached by anyone in

  1. the last row 
  2. the fourth row
  3. the fourth column
  4. the middle column

58. Which of the following statements is true about this layout?

  1. Each row has an individual who can be reached by 5 or more individuals
  2. Each row has an individual who cannot be reached by anyone
  3. Each row has at least two individuals who can be reached by an equal number of individuals
  4. All individuals at the height of 9 m can be reached by at least 5 individuals

The set is definitely non-standard.

Conditions are neither plugin nor deductive but directions.

The set is fully closed since there is no additional information in the questions.

Non-Standard, Directions, Closed.

I would rate this an 8 out of 10.

When I take a look at the questions, I know that since the set is so simple, they will test every part of the platform. In other words, I will be best served by just drawing a new table where instead of the height I have how many can reach it.

Screen Shot 2018-10-31 at 12.27.05 PM.png

This done with full concentration will take 5 minutes after this you can just tick off the answers. I suggest doing this on your own to see how prone you are to making silly mistakes.

This set should give you 12 marks in 10 minutes.

We have a total of 48 marks and have almost reached the end of the time-limit.


The Airlines Set

A new airlines company is planning to start operations in a country. The company has identified ten different cities which they plan to connect through their network to start with. The flight duration between any pair of cities will be less than one hour. To start operations, the company has to decide on a daily schedule.

The underlying principle that they are working on is the following:

Any person staying in any of these 10 cities should be able to make a trip to any other city in the morning and should be able to return by the evening of the same day.

59. If the underlying principle is to be satisfied in such a way that the journey between any two cities can be performed using only direct (non-stop) flights, then the minimum number of direct flights to be scheduled is:

  1. 45
  2. 90
  3. 180
  4. 135

60. Suppose three of the ten cities are to be developed as hubs. A hub is a city which is connected with every other city by direct flights each way, both in the morning as well as in the evening. The only direct flights which will be scheduled are originating and/or terminating in one of the hubs. Then the minimum number of direct flights that need to be scheduled so that the underlying principle of the airline to serve all the ten cities is met without visiting more than one hub during one trip is:

  1. 54
  2. 120
  3. 96
  4. 60

61. Suppose the 10 cities are divided into 4 distinct groups 01,02,03,04 having 3, 3, 2 and 2 cities respectively and that G1 consists of cities named A, B and C. Further, suppose that direct flights are allowed only between two cities satisfying one of the following:

  1. Both cities are in G1
  2. Between A and any city in G2
  3. Between B and any city in G3
  4. Between C and any city in G4

Enter your response as an integer using the virtual keyboard.

62. Suppose the 10 cities are divided into 4 distinct groups G1, G2, G3, G4 having 3, 3, 2 and 2 cities respectively and that G1 consists of cities named A, B and C. Further, suppose that direct flights are allowed only between two cities satisfying one of the following:

  1. Both cities are in G1
  2. Between A and any city in G2
  3. Between B and any city in G3
  4. Between C and any city in G4

However, due to operational difficulties at A, it was later decided that the only flights that would operate at A would be those to and from B. Cities in G2 would have to be assigned to G3 or to G4.

What would be the maximum reduction in the number of direct flights as compared to the situation before the operational difficulties arose?

Enter your response as an integer using the virtual keyboard.

The set is a standard routing set and we have seen many of this type of. Is this a LR set or a P&C Set? Definitely P&C.

Conditions are again directions.

It is an open set since conditions are given in the questions and you are not filling a table or completing any representation.

This is a set that can be read quickly and the first two questions can be attempted very fast. But the catch is that one can also make mistakes very fast since one approaches the set from a P&C space. Even if you attempt this set, questions 3 and 4 are time-taking and tricky.

I would rate this a 7 out of 10 and solve only the first 2 questions and exit the set.

Question 59: We can choose two cities out of 10 cities in 10C2 or 45 ways. Between any two cities, you need two flights each in the morning and at night. So the total number of flights needed are 45*4 = 180.

Question 60: You need flights between hubs in the same way as in the previous question so that will be 3C2*4 = 12. Between each of the 3 hubs and the 7 cities you need flights, each hub is connected to 7 cities so 3 hubs have 21 connection. For each connection, you need two flights each in the morning and at night, making the total flights between hubs and cities 21*4 = 84. The total number of flights will be 96.


The Car Routes Set

Four cars need to travel from Akala (A) to Bakala (B). Two routes are available, one via Mamur (M) and the other via Nanur (N). The roads from A to M, and from N to B, are both short and narrow. In each case, one car takes 6 minutes to cover the distance, and each additional car increases the travel time per car by 3 minutes because of congestion. (For example, if only two cars drive from A to M, each car takes 9 minutes.) On the road from A to N, one car takes 20 minutes, and each additional car increases the travel time per car by 1 minute. On the road from M to B, one car takes 20 minutes, and each additional car increases the travel time per car by 0.9 minutes.

The police department orders each car to take a particular route in such a manner that it is not possible for any car to reduce its travel time by not following the order, while the other cars are following the order.

63. How many cars would be asked to take the route A-N-B, that is Akala-Nanur-Bakala route, by the police department?

Enter your response as an integer using the virtual keyboard.

64. If all the cars follow the police order, what is the difference in travel time (in minutes) between a car which takes the route A-N- B and a car that takes the route A-M-B?

Enter your response as an integer using the virtual keyboard.

65. A new one-way road is built from M to N. Each car now has three possible routes to travel from A to B: A-M-B, A-N-B, and A-M- N-B. On the road from M to N, one car takes 7 minutes and each additional car increases the travel time per car by 1 minute. Assume that any car taking the A-M-N-B route travels the A-M portion at the same time as other cars taking the A-M-B route, and the N-B portion at the same time as other cars taking the A-N-B route.

How many cars would the police department order to take the A-M-N-B route so that it is not possible for any car to reduce its travel time by not following the order while the other cars follow the order? (Assume that the police department would never order all the cars to take the same route.)

Enter your response as an integer using the virtual keyboard.

66. A new one-way road is built from M to N. Each car now has three possible routes to travel from A to B: A-M-B, A-N-B, and A-M- N-B. On the road from M to N, one car takes 7 minutes and each additional car increases the travel time per car by 1 minute. Assume that any car taking the A-M-N-B route travels the A-M portion at the same time as other cars taking the A-M-B route, and the N-B portion at the same time as other cars taking the – A-N-B route.

If all the cars follow the police order, what is the minimum travel time (in minutes) from A to B? (Assume that the police department would never order all the cars to take the same route.)

  1. 26
  2. 32
  3. 29.9
  4. 30

This set can be seen as a variation of the fast food set, but with more complexity. If I rated that as an 8 this would at best a 6.5 out of 10.


What should be your order of attempting the sets?

Let’s do a recap of the 8 sets.

Set 1: The Fast Food Joint — Non-Standard, Plugin, Closed — 9/10 

Set 2: The Education Survey — Standard, Plugin, Closed — 7/10

Set 3: The Entrance Test — Non-Standard, Deductive, Open — 6/10

Set 4: The Happiness Index — Standard, Deductive, Open — 6/10

Set 5: The Projects Set — Non-Standard, Directions, Closed — 7.5/10

Set 6: The Platform — Non-Standard, Directions, Closed — 8/10

Set 7: The Airlines — Standard, Directions, Open — 7/10

Set 8: The Car Routes — Standard, Directions, Open — 6.5/10

Now there are two ways for you to go about the section

  • Read & rate all 8 sets start from the easiest set
  • Read & rate the first 4 sets, do only the 8/10 sets and then scan and rate the next 4 and do the 8/10 sets and then do the sets in decreasing order of ratinG

Remember that sets appear in randomized order to different candidates.

Suppose you read and rate the first four sets and have 7,6,7,6 as your ratings and go ahead and take 30 minutes to solve the two 7s without getting stuck.

The next four have 8,8,8,7. What position would you rather be in the last 30 minutes?

  • 36 marks and two more sets to crack or
  • 24 marks and three more sets to crack

I would always want to be in the first position since the last 15 minutes usually tend to be rushed and there is a high chance that one will make silly mistakes.

I will rather have known that early about the three 8s mean and figure that the cut-off will be high and hence be in a much better position to get two right sets in last 30 minutes.

By either method in this section, my order will be

  1. The Fast Food Joint, 4 questions
  2. The Platform Set, 4 questions
  3. The Projects, 4 questions
  4. The Education Survey, 4 questions
  5. The Airlines, 2 questions

What score was realistically possible

All test-takers should have got at least the Fast Food, Platform sets right. If you just did these two and wasted all the rest of your time, you will still have got 24 marks!

A test-taker who is currently scoring around 85 percentile in the SimCATs should have got at least 3 sets out of 5 we shortlisted and scored 36 marks.

A test-taker scoring around 95 percentile and above on the SimCATs could have got 4 sets right and scored 48.

A test-taker scoring a 99-plus on the SimCATs could have answered 18 questions and scored 54.

Even If we account for silly mistakes, test-takers should and could have scored 20, 28, 40 and 46 at the above-mentioned percentiles.

These are raw scores we are talking about and since Slot 1 was tougher than Slot 2 your scaled scores will have been higher than the raw scores.

A scaled score of

  • 24 was approximately 85 percentile
  • 28 was approximately 90 percentile
  • 34 was approximately 95 percentile
  • 44 was approximately 99 percentile

So a 54 raw would have been scaled higher and corresponded to a percentile of 99.99.


What made so many people fumble?

3 out of the 4 do-able sets were Non-Standard!

The main roadblock to right selection always goes back to familiarity.

Many test-takers will have chosen The Airlines, the Car Routes and may be the Entrance Test sets to solve since they are familiar.

Test-takers have an inborn bias towards choosing familiar LR but tough LR over DI and unfamiliar LR.

I keep wondering what makes everyone think they are good at LR?

Do all of these people solve a MEDIUM Sudoku puzzle in under 3:30 every single time and a HARD one in under 5:30? I am sure only a few will say YES to both questions.

The writing is on the wall — you will not get 4 Standard LRs that you can solve on auto-pilot!

CAT DI-LR is getting difficult because

  • they are throwing up non-standard sets that need to be read slowly to be really understood — The Platform and The Projects sets
  • even the easy sets needed to be solved with workman-like effort and surgeon-like precision — The Projects Set, Platform Set, The Chess Set
  • they are setting up some really good DI sets that need you to figure out what’s missing at a top-level — row or column — and not what’s missing in the cells — The Education Survey, The Pizza Set
  • they are introducing Math-LR sets — The Happiness Index Set, The Dormitory Set, The Old Woman and her Wealth, The Tea Tasting Set, The Airline Seating Set

So what’s the verdict?

Is it as tough as everyone is making it out to be? No.

Is it along the lines that everyone wants it to be? No.

My friend did not kill the section as he customarily does because he was woefully short of sleep because the paper wasn’t really that tough.


Hope the three posts on DI-LR has given you a comprehensive picture of what the section is testing.

One of the readers correctly identified that a big part of cracking DI-LR is how we represent the data on the rough sheet and how it sometimes doesn’t always click.

Let me know through the comments if you want me to do a post specifically on how to find the best representation for the given data and why it’s not a matter of clicking but a matter of how one gets into position to play a shot.

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4 Comments

  1. Ashutosh Sinha says

    Yes, sir. Please do that post.
    And sir I want to know that how much time(maximum) should we invest in rating the sets. Many times, I invest around 6-8 mins. Am I taking too long?
    And what is the ideal time in which we should leave a set that we tried attempting but can’t find the logic.

    Like

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