Time, Speed & Distance
Aptitude

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Q.

A boatman rows to a place 45 km distant and back in 20 hour. He finds that he can row 12 km with the stream in the same time as 4 km against the stream. Find the speed of the stream.

 A.

3 km/hr

 B.

2.5 km/hr

 C.

4 km/hr

 D.

3.5 km/hr

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Solution:
Option(A) is correct

Ratio of time taken for up and down = $3:1$

Out of 20 hr he took 15 hr for up and 5 for down.

Speed up = \(\dfrac{45}{15}=3\)

and down = \(\dfrac{45}{5}=9\)

Hence speed of stream 

\((9−3)\times \dfrac{1}{2}\)

3 km/hr

 


(1) Comment(s)


NerdBird
 ()

Was it supposed to be (9-3) x 1/2?