A train has length of 150 meters. It is passing a man who is moving at 2 km/hour in the same direction of the train, in 3 seconds. Find out the speed of the train?
Lisa gives her little brother Sam a 15-second (sec) head start in a 300-meter (m) race. During the race. Sam runs at an average speed of 5 m/sec and Lisa runs at an average speed of 8 m/sec, not including the head start. Since the time Lisa started running, what is the best approximates the number of seconds that had passed when Lisa caught up to Sam?