Question

A boy can swim in still water at a speed of 10 km/hr. If the speed of the current would have been 5 kmph, then the boy could swim 60km

• A. upstream in 4 hour
• B. downstream in 12 hours
• C. upstream in 6 hours
• D. downstream in 4 hours

Answer 1

Answer:

D. downstream in 4 hours

Given:

Still Water Speed = 10 kmph

Speed of Current = 5kmph

Distance = 60 km

Calculation:

Rate downstream = 10 + 5 = 15 kmph

Rate upstream = 10 – 5 = 5 kmph

Time taken in swimming 60km downstream

$=\frac{60}{15}=4hours$

15 = 4 hours

Time taken in swimming 60km upstream

$=\frac{60}{5}=12hours$

From, given options, boy can swim 60km downstream in 4 hrs.