Two balls a and b rotate along a circular track. ball a makes 4 full rotations in 120 seconds. ball b makes 3 full rotation in 60 seconds. if they start rotating now from the same point, when will they be at the same starting point again?

Find the rate in which both balls make one full rotation around the track.

Ball A:



It takes 30 seconds for Ball A to make a full rotation.

Ball B:



It takes 20 seconds for Ball B to make a full rotation.

Find the least common multiple of 20 and 30 to find the time at which they'll meet.

Multiples of 20: {20,40,60}
Multiples of 30: {30,60}

60 is the least common multiple of both 20 and 30.

The balls will meet again at 60 seconds.

The answer for this question is 80