Question

In a row of boys, If A who is 10th from the left and B who is 9th from the right interchange their positions, A becomes 15th from the left. How many boys are there in the row?

A) 23
B) 31
C) 27
D) 28

Answer 1

The total number of boys in the row is 23. This conclusion is reached by adding A's position after the swap (15th from the left) to B's initial position (9th from the right) and subtracting 1 to account for their shared position, resulting in 23 boys in total.

Step-by-step explanation:

The question involves finding out the total number of boys in a row based on the given positions before and after two boys, A and B, swap places. Initially, A is the 10th boy from the left, and B is the 9th from the right. After they interchange their positions, A becomes the 15th from the left.

To solve this, we recognize that when A moves to B's original position and becomes the 15th from the left, it implies that there were 5 boys between A's original position (10th from the left) and B's original position (before swapping). So B's position from the right does not change after the swap, meaning B was initially the 15th boy from the left. B being 9th from the right can help us calculate the total number of boys.

Since B is 9th from the right and also was the 15th boy from the left originally, we add these positions together and subtract 1 (to avoid double-counting B himself) to find out the total number of boys. Thus, the calculation is 15 + 9 - 1, which equals 23. Therefore, the total number of boys in the row is 23 (Option A).