Question

In a row at a bus stop, 'A' is 7th from the left and 'B' is 9th from the right. They both interchange positions. Now A becomes 11th from the left. How many people are there in the row?

• A. 14
• B. 16
• C. 17
• D. 19
• E. 18

Hint:

When two people interchange, the new position of the first person and the old position of the second person refer to the same physical spot.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
When two people interchange positions, the new position of one person gives us both the "Left" and "Right" rank for that specific spot.
Step 2: Identifying the Vector of Change:
- Initially, A is 7th (Left) and B is 9th (Right). - They swap. Now A is standing where B was. - Therefore, A is now in a spot that we already know is 9th from the Right.
Step 3: Calculation:
- The statement says after the swap, A is 11th from the Left. - We also know this spot is 9th from the Right (from B's original position). - Total People = (Position from Left + Position from Right) - 1 - Total = $(11 + 9) - 1 = 20 - 1 = 19$.
Step 4: Final Answer:
The total number of people in the row is 19. Thus, the correct option is (d).