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?

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:

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