A man can row 1.8 kilometer against the stream in 15 minutes and down the stream in 3 minutes. The speed (in m/sec) of the man in still water is-

Question: A man can row 1.8 kilometer against the stream in 15 minutes and down the stream in 3 minutes. The speed (in m/sec) of the man in still water is-

Solution:
1.8 kilometer = 1800 meters
15 minutes = 15 × 60
= 900 sec
3 minutes = 3 × 60
= 180 sec
Rate upstream = 1800/900 m/sec
= 2 m/sec
Rate downstream = 1800/180 m/sec
= 10 m/sec
∴ Rate in still water = (1/2)(2 + 10) m/sec
= 6 m/sec