From a point on a circular track 10 km long A, B and C

Solution

∵ Total time taken = Total distance/Average speed ∴ Time taken by A to complete one round =10/3(1/3) = 3 hours = 3 × 60 mins = 180 minutes ∴ Time taken by B to complete one round =10/5 hours = 10/5 × 60 mins = 120 minutes ∴ Time taken by C to complete one round = 10/2 hours = 10/2 × 60 mins = 300 minutes ∴ Time taken by all three to meet again at the starting point = LCM of 180, 120 and 300 minutes = 600 minutes = 1800/60 hours = 30 hours