Question

A person can row 3/5 of a km in upstream in 10 minutes and return in 6 minutes. Find the speed of man
in still water?
1) 4.4 kmph
3) 4.8 kmph
4.5 kmph
4.9 kmph​

Answer 1

Complete question:

A person can row 3/5 of a km in upstream in 10 minutes and return in 6 minutes. Find the speed of man in still water?

1) 4.4 kmph 2) 4.5 kmph 3) 4.8 kmph 4) 4.9 kmph​

The answer to this question is option (3) 4.8 kmph

Given:

Time taken by a person to row upstream = 10 minutes

Time taken by a person to row downstream = 6 minutes

Total distance to be covered = 3/5 km

To Find:

The speed of man in still water =?

Solution:

Let the speed of the man in still water be x and

the speed of the stream be y.

The speed of the man downstream = x + y

The speed of the man upstream = x - y

We know that distance = speed × time

The person can row 3/5 km downstream in 6 minutes.

6 minutes = 1/10 hr

$\frac{3}{5} = (x + y) \frac{1}{10}$

x + y = 6 -------------(1)

The person can row 3/5 km upstream in 10 minutes.

10 minutes = 1/6 hr

$\frac{3}{5} = (x - y) \frac{1}{6}$

x - y = 18/5 -----------(2)

Adding equations (1) and (2), we get

x + y + x - y = 6 + $\frac{18}{5}$

2x = $\frac{30 +18}{5}$

2x = $\frac{48}{5}$

x = $\frac{24}{5}$

x = 4.8

Hence, the speed of man in still water is 4.8 kmph

The answer to this question is option (3) 4.8 kmph

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