CAT LRDI Set with Video Solution 04

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 in the following manner. They obtain the 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 sources 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.

Question: Which one among the following must have two sources

[1] A
[2] B
[3] C
[4] D
Option: 2

Question: 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
Option: 3

Question: Both G and H were sources to

[1] F
[2] B
[3] I
[4] None of the nine
Option: 4

Question: 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.
Option: 3

Question: Which of the following two groups of people had 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
Option: 4

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