A man rows a boat 18 km in 4 hr downstream and returns upstream in 12 hr The speed of the stream in ...........

Quantitative Aptitude ( CCS) Boats and Streams

A man rows a boat 18 km in 4 hr downstream and returns upstream in 12 hr. The speed of the stream (in km/hr)

1.5

1.75

Rate downstream = $\frac{18}{4}=\frac{9}{2} km/hr$

Rate upstream = $\frac{18}{12}=\frac{3}{2} km/hr$

Now, speed of the stream = $\frac{Rate Downstream - Rate Upstream }{2}$

$=>\frac{\frac{9}{2}-\frac{3}{2}}{2}=\frac{6}{4}=\frac{3}{2}$

$=>1.5 km/hr$

Hence, option 2 is the correct answer.

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