Three persons P, Q, R run along a circular track at speeds of 3 km/h, 4 km/h, 6 km/h, respectively. If the length of the track is 36 km, then after how much time will they meet again, at the starting point?
(a) 32
(b) 36
(c) 45
(d) 50
Sol:
Speed of P, Q and R = 3 km/h, 4 km/h, 6 km/h respectively
Length of track = 36 km
Concept Used: Speed = Distance / Time Calculation:
⇒ Time taken by P to cover the track = 36/3 = 12 hrs
⇒ Time taken by Q to cover the track =36/4 = 9 hrs
⇒ Time taken by R to cover the track = 36/6 = 6 hrs
⇒ LCM of 12, 9 and 6 = 36
Therefore, they all will meet again at the starting point after 36 hours.
