Question

Q.15. A man can swim with the stream at the rate of 3 kmph
and against the stream at the rate of 2 kmph. How
long will it take him to swim 7 km in still water?
1) 3 hours 2) 2.8 hours 3) 2.6 hours
4) 3.2 hours 5) None of these​

Answer 1

Answer:

2)2.8 hours

Step-by-step explanation:

with the stream =3 kmph

against the stream= 2 kmph

still water = avg of 3 and 2 =2.5 kmph

distance=7km

speed=2.5kmph

time=7/2.5

=2.8h

Hope this will help you !

Good Luck

Answer 2

The correct option is 2.

Step-by-step explanation:

Let x be the man's speed in still water.

y be the speed of water.

A man can swim with the stream at the rate of 3 kmph and against the stream at the rate of 2 kmph.

$x+y=3$

$x-y=2$

Add both equations.

$2x=5$

$x=\dfrac{5}{2}=2.5$

Speed of man is 2.5 kmph.

Formula for time:

$Time=\dfrac{Distance}{Speed}$

Distance is 7km  and speed is 2.5 kmph.

$Time=\dfrac{7}{2.5}$

$Time=2.8$

Therefore, the correct option is 2.

#Learn more

A boy can swim in still water at 4.5 km/h, but takes twice as long to swim upstream than downstream. The speed of the stream is ?

A) 1.8 kmph

B) 2 kmph

C) 2.2 kmph

D) 1.5 kmph

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