A and B walk around a circular track. They start at 8 a.m. from the same point in the opposite directions. A and B walk at a speed of 2 rounds per hour and 3 rounds per hour, respectively. How many times shall they cross each other before 9.30 a.m.?

A and B walk at a speed of 2 rounds per hour and 3 rounds per hour.

They are walking around a circular track.

They started walking at 8:00 a.m from the same point in opposite directions.

In a circular track, when A and B are walking in opposite directions, the net speed = Speed of A + Speed of B.

We assume, A to be at rest, so speed of B will be = 3+2 = 5 rounds per hour.

So, from 8 to 9:30, in one and half hour, the number of rounds taken by B will be = 5*1.5 = 7.5 round.

Since, 7 rounds are completed, therefore, A and B will cross each other 7 times in this duration.