Question

Speed of a boat in standing water is 12 kmph and the speed of the stream is 3 kmph. A man rows to a place at a distance of 6300 km and comes back to the starting point. The total time taken by him is:

• A. 1120 hrs
• B. 1000 hrs
• C. 980 hrs
• D. 850 hrs

Answer 1

Answer:

A. 1120 hrs

Explanation: 

Downstream speed = (12 + 3) = 15 km/hr

Upstream speed = (12 – 3) = 9 km/hr

Total time taken $=\frac{6300}{15}+\frac{6300}{9}$

= 420+700 ==> 1120hrs.