SSC CPO 2022 PYQ — Question 149

The correct answer is Option 2 i.e. $\rm 1\frac{4}{9} \ hours$.

We know that,

Downstream speed = x + y 

where the boat's speed in still water is x and the speed of the stream is y.

Now, according to the question:

104/(x + y) = 8

⇒ x + y = 13

y = 2 (given)

⇒ x = 13 - y = 13 - 2 

⇒ x = 11

So,

Upstream speed = x - y = 11 - 2 = 9 km/h

Distance = Speed × Time

⇒ 13 = 9 × Time

Time = 13/9 = $\rm 1\frac{4}{9} \ hours$

Therefore, the time taken to cover 13 km upstream is $\rm 1\frac{4}{9} \ hours$.