Q28
ArithmeticSpeed, Time & Distance
Two boats A and B start towards each other from two places, 108 km apart. Speeds of the boats A and B in still water are 12 km/hr and 15 km/hr respectively. If A proceeds down and B up the stream, they will meet after:
- a.4·5 hours
- b.4 hours
- c.5·4 hours
- d.6 hours
Answer: (B) 4 hours
A's speed is (12 + s) and B's is (15 − s) for stream speed s, so their closing speed is 27 km/hr whatever s is. They meet after 108 ÷ 27 = 4 hours. 4·5 and 6 hours would need a slower closing speed.