Question

$A$ walks around a circular field at the rate of one round per hour while $B$ runs around it at the rate of six rounds per hour. They start in the same direction from the point at $7.30$ $a.m.$ They shall first cross each other at:

• A. $7.42$ $a.m.$
• B. $7.48$ $a.m.$
• C. $8.10$ $a.m.$
• D. $8.30$ $a.m.$

Answer 1

The correct option is A $7.42$ $a.m.$

Since, A and B move in the same direction along the circle, so they will first meet, each other when there is a difference of one round between the two.
Relative speed of A and B $=(6-1)=5$ rounds per hour.
Time taken to complete one round at this speed $=\frac{1}{5}hr=12min.$
Hence, They shall first cross each other at $7.42am.$