A man’s speed in still water is 4 km/h more than the speed of the current. If the man takes a total of 10 h to cover 45 km downstream and 35 km upstream, then the speed of the man in still water is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e. 20 km/h.
Let the speed of the current be x km/h
Hence speed of man = (x + 4) km/h
He travels 45 km downstream and 35 km upstream in 10 hours
Relative speed traveling downstream = x +4 +x = 2x +4
Relative speed traveling upstream = x + 4 - x =4
Formula used
Time =
10 =
Solving for x we get
x = 16 km/h
Hence the speed of the man = 16 + 4 = 20 km/h.