A and B walk around a circular track. A and B walk at a speed of 2 rounds per hour and 3 rounds per hour respectively. If they start at 8 a.m. from the same point in opposite directions, how many times shall they cross each other before 9.30 a.m.?
5
6
7
8
Explanation:
Relative speed = Speed of A + Speed of B (∴ they walk in opposite directions)
=2+3=5 rounds per hour
Therefore, they cross each other 5 times in 1 hour and 2 times in 12 hour
Time duration from 8 a.m. to 9.30 a.m. =1.5 hour
Hence they cross each other 7 times before 9.30 a.m.
Relative speed = Speed of A + Speed of B (∴ they walk in opposite directions)
=2+3=5 rounds per hour
Therefore, they cross each other 5 times in 1 hour and 2 times in 12 hour
Time duration from 8 a.m. to 9.30 a.m. =1.5 hour
Hence they cross each other 7 times before 9.30 a.m.