Three friends A, B and C run around a circular track of length 120 metres at speeds of 5 m/s, 7 m/sec and 15 m/sec, starting simultaneously from the same point and in the same direction. How often will the three of them meet?

A car travels a distance of 360km at a uniform speed. If speed of the car is 20km/hr more then time is 3 hrs. less.The original speed of car was:

In a watch, the minute hand crosses the hour hand for the third time exactly after every 3 hrs 18 min 15 seconds of watch time. What is the time gained or lost by this watch in one day?

A man in a train notices that he can count 21 telephone posts in one minute. If they are known to be 50 metres apart, then at what speed in the train travelling?

A Boat running downstream covers a distance of 16 km in 2 hours while for covering the same Distance upstream it takes   4 hours. What is the speed of the boat in still water?