SSC Sample Paper Mock Test-11 SSC CGL Tear-II Paper-1

A steamer goes downstream from one port to another in 4 h. It covers the same distance upstream in 5 h. If the speed of stream is 2 km/h, the distance between the two ports is

A) 50 km

B) 60 km

C) 70 km

D) 80 km

Correct Answer: D

Solution :

Let the distance between two parts be x km.

Let the speed of steamer in still water y km/h.

\[\therefore \] \[\frac{x}{y+2}=4\] ?(i)

and \[\frac{x}{y-2}=5\] ?(ii)

From Eqs. (i) and (ii),we get

\[4\,\,(y+2)=5(y-2)\]

\[\Rightarrow \] \[4y+8=5y-10\]

\[\Rightarrow \] \[5y-4y=10+8\]

\[\Rightarrow \] \[y=18\,\,\text{km/h}\]

From Eq. (i),

\[\frac{x}{18+2}=4\]

\[\Rightarrow \] \[x=4\times 20=80\,\,\text{km}\]