Dear students,
The topic for the day is “Data Arrangement” and currently lots of questions have been asked from this topic in CAT. Today we have picked up a set from CAT 2003 for practice.

DIRECTIONS: Answer the questions on the basis of the following information.

Recently, the answers of a test held nationwide were leaked to a group of unscrupulous people. The investigative agency has arrested the mastermind and nine other people A, B, C, D, E, F, G, H and I in this matter. Interrogating them, the following facts have been obtained regarding their operation. Initially the mastermind obtains the correct answer-key. All the others create their answer-key from one or two people who already possess the same. These people are called his/her “sources”. If the person has two sources, then he/she compares the answer-keys obtained from both sources. If the key to a question from both sources is identical, it is copied, otherwise it is left blank. If the person has only one source, he/she copies the source’s answers into his/her copy. Finally, each person compulsorily replaces one of the answers (not a blank one) with a wrong answer in his/her answer key.
The paper contained 200 questions; so the investigative agency has ruled out the possibility of two or more of them introducing wrong answers to the same question. The investigative agency has a copy of the correct answer key and has tabulated the following data. These data represent question numbers.

1.Which one among the following must have two sources?
(1) A
(2) B
(3) C
(4) D

2. How many people (excluding the mastermind) needed to make answer keys before C could make his answer key?
(1) 2
(2) 3
(3) 4
(4) 5

3. Both G and H were sources to
(1) F
(2) B
(3) I
(4) None of the nine.

4. Which of the following statements is true?
(1) C introduced the wrong answer to question 27.
(2) E introduced the wrong answer to question 46.
(3) F introduced the wrong answer to question 14.
(4) H introduced the wrong answer to question 46.

5. Which of the following two groups of people has identical sources?
(I) A, D and G (II) E and H

(1) Only (I)
(2) Only (II)
(3) Neither (I) nor (II)
(4) Both (I) and (II)

Solution :-

1. If there are two sources, then possibility of blank answers increases. ‘ B’, ‘C’ and ‘I’ are having three blanks. ‘I’ is not in the answer. Only B is possible as he has only one wrong and it may have E and G as a source. C may have only a single source, I, as the wrong and blank questions are the same, with an addition of wrong question
2. C has blank at 17, 46, 90 and two wrong at 27, 56.
   It can be possible by only I. If D and E make copy, then 17, 46, 90 get blank. After that, C makes wrong. E can prepare its answer-key by using data from A. So, it can also make it before C.
3. If G and H are sources, then their wrong answers get converted to blank, i.e. 25, 46, 92. No one has the same blank.
4. For F, there are two wrong answers (14, 46) and two blanks (92, 90). This will be possible by only E and H. Both these are having the same wrong option for 46 that will be forwarded by F. As per condition, he again makes one wrong answer and that must be 14.
5. Observe their blank source, all have same no of blank. & Observe wrong, each one in-group has it same no. So both groups have same source.

Set analysis:-
Level of difficulty:- Moderate to Difficult
Expected time to solve:- 10 to 12 minutes.

Hope you learnt!
See you with the next one tomorrow!
Happy learning!
Gajendra sir
CAT Coach