Question

In a fixed time, a boy swims double the distance along the current that he swims against the current. If the speed of the current is 3 km/hr, the speed of the boy in still water is

• A. 6 km/hr
• B. 9 km/hr
• C. 10 km/hr
• D. 12 km/hr

Answer 1

Answer:

B. 9 km/hr

Let the rate of swimming in still water be x kmph

Rate down-stream = (x + 3) kmph

Rate up-stream = (x – 3) kmph

According to the question,

$(x + 3) t = 2 (x-3)\times{t}$

x + 3 = 2x – 6

2x-x=3+6

x = 9 kmph