Question 55

The speed of a boat in still water is 30 km/h. If the boat covers 60 km downstream in 1 hour 30 minutes, then what is the time taken by the boat to cover 60 km upstream?

Solution

Distance = Speed $$\times$$ Time

The boat covers 60 km downstream in 1 hour 30 minutes . Let the speed of stream be s km/hr.

$$\frac{60\ }{30+s}\ =\ 1.5$$

30+s = 40

s = 40-30

s = 10 km/hr

Upstream speed = 30 - 10 = 20 km/hr

Time taken by the boat to cover 60 km upstream = $$\frac{60}{30 - 10}$$ = 3 hours

So, the answer would be option a)3 hours

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