SSC Sample Paper Mock Test-18 SSC CGL Tear-II Paper-1

A man can row 30 km upstream and 44 km downstream in 10 h. Also, he can row 40 km upstream and 55 km downstream in 13 h. Find the speed of the man in still water.

A)          8 km/h

B) 6 km/h

C) 9 km/h

D) 10 km/h

Correct Answer: A

Solution :

Let speed upstream be x km/h and the speed' downstream be y km/h.

Then, \[\frac{30}{x}+\frac{44}{y}=10\] ?(i)

and \[\frac{40}{x}+\frac{55}{y}=13\]

Multiplying Eq. (ii) by 4, Eq. (i) by 5 and subtracting, we get,\[\frac{10}{x}=2\] \[\Rightarrow \]\[x=5\]

Putting x = 5 in Eq. (i), we get \[4y=44\]

\[\Rightarrow \]\[y=11\]

\[\therefore \]Speed upstream = 5 km/h, speed downstream =11 km/h

Speed of the current \[=\frac{1}{2}(11-5)\,\text{km/h}=3\,\,\text{km/h}\]

Speed of man in still water

\[=\frac{1}{2}(11+5)\,\text{km/h}=8\,\,\text{km/h}\]