Question 64

Logical Reasoning Puzzles Easy

Nine individuals - Z, Y, X, W, V, U, T, S and R - are the only candidates, who can serve on three committees-K1, K2 and K3, and each candidate should serve on exactly one of the committees. Committee K1 should consist of exactly one member more than committee K2. It is possible that there are no members in committee K3. Among Z, Y and X none can serve on committee K1. Among W, V and U none can serve on committee K2. Among T, S and R none can serve on committee K3. In case committee K2 is served by T and Z only, how many of the nine individuals should serve on committee K3? 

(A) 3
(B) 4
(C) 5
(D) 6
View Dynamic Solution & Explanation
Correct Solution: Option B

Step-by-step Solution:

Step-by-Step Logical Deduction

To solve this puzzle, we can use the given rules about the sizes of the committees, combined with the specific condition provided in the question.

1. Analyzing the Rules about Committee Sizes

We are given two fundamental rules regarding the number of members (size) in each committee:

  • Rule 1: Size(K1) = Size(K2) + 1
  • Rule 2: Size(K1) + Size(K2) + Size(K3) = 9

We can substitute the first rule into the second rule to create a single equation relating the sizes of committees K2 and K3:

(Size(K2) + 1) + Size(K2) + Size(K3) = 9

2 × Size(K2) + Size(K3) = 8

2. Applying the Specific Condition

The question provides a specific scenario to consider: "In case K2 is served by T and Z only".

This statement means that Committee K2 consists of exactly two members, T and Z.

So, for this scenario, Size(K2) = 2.

3. Calculating the Size of Committee K3

Now we can substitute Size(K2) = 2 into our combined equation:

2 × (2) + Size(K3) = 8

4 + Size(K3) = 8

Size(K3) = 8 - 4

Size(K3) = 4

Conclusion

Based on the given conditions, the number of individuals who should serve on committee K3 is 4.