Boats and Streams | Arithmetic aptitude | Discussion Page

What the speed of the man in still water?

I. The man can swim a distance of $48$ kms in $6$ hours with upstream.

II. The man can swim the same distance in $4$ hours with downstream.

A) I alone sufficient while II alone not sufficient to answer

B) II alone sufficient while I alone not sufficient to answer

C) Either I or II alone sufficient to answer

D) Both I and II are not sufficient to answer

E) Both I and II are necessary to answer

Option E

I. Speed upstream $=\frac{48}{6}$ km/hr $=8$ km/hr.

II. Speed downstream $=\frac{48}{4}$ km/hr $=12$ km/hr.

Speed of the boat $=\frac{1}{2}(8+12)$ km/hr $=10$ km/hr.

Thus, I and II together give the answer.

$\therefore$ Correct answer is (E).

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