Row of boys facing North – A is 16th from the left; C is 16th from the right. B is fourth to the right of A and fifth to the left of C. How many boys are in the row?
Verbal Reasoning
Time Sequence
Difficulty: Medium
Choose an option
-
A39
-
B40
-
C41
-
D42
-
ENone of these
Answer
Correct Answer: 40
Explanation
Introduction / Context:We have linked positions. Convert each relational clue into an absolute position from the left, then use the dual rank of C to get the total.
Given Data / Assumptions:
- pos(A) from left = 16.
- B is 4 to the right of A → pos(B) = 16 + 4 = 20.
- B is 5 to the left of C → pos(C) = 20 + 5 = 25 (from left).
- C is 16th from the right.
Concept / Approach:If C is rth from the right and kth from the left, total N = r + k − 1. Plug r = 16 and k = 25.
Step-by-Step Solution:
Compute pos(B) = 20.Compute pos(C) = 25.Total N = 16 + 25 − 1 = 40.Verification / Alternative check:From N = 40, C’s right-rank is 40 − 25 + 1 = 16, matching the given.
Why Other Options Are Wrong:39/41/42 mismatch the computed identity with the fixed positions.
Common Pitfalls:Placing B “to the left” instead of “to the right,” or forgetting −1 in N = left + right − 1.
Final Answer:40