## Q 30/70 A motor boat covers a certain distance downstream in a river in 1 hours. It covers the same distance upstream in 5 hours.

Question

Q 30/70 A motor boat covers a certain distance

downstream in a river in 1 hours. It covers

the same distance upstream in 5 hours. The speed

of the water is 6.0 km/hr. The speed of the boat in

still water is:

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2021-10-08T05:16:21+00:00
2021-10-08T05:16:21+00:00 2 Answers
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## Answers ( )

Given :–To Find :-Solution :-Let,The distance covered = s.

The speed of boat in still water = x km/hr.

We know that,Given that,Net speed of boat in downstream= x + 6

=> s = (x + 6) × 1

=> s = x + 6 ……….(i)

Also given that,The same distance upstream in 5 hours= x – 6

=> s = (x – 6) × 5

=> s = 5x – 30 ………..(ii)

Form equation (i) and (ii),s = (x – 6) = (5x – 30)

=> x + 6 = 5x – 30

=> x – 5x = -30 – 6

=> -4x = -36

=> x = -36/-4

=>

x = 9 km/hrAnswer :-The speed of the boat in still wateris 9km/hr.EXPLANATION.A motor boat covers a certain distance

downstream in a river in 1 hours.

it coveres the same distance upstream in

5 hours .

The speed of the water is = 6 km/hr.

## To find the speed of the boat in still

## water?

Accordingtothequestion,Let the distance covered = s

Let speed of boat in still water = x km/hr.

## As we know that,

## => Distance = Speed X Time

Time taken for downstream = 1 hours.

Net speed of boat in downstream

=> ( x + 6 )

=> s = ( x + 6 ) X 1

=> s = ( x + 6 ) …..(1)

Time taken for upstream = 5 hours.

Net speed of boat in upstream.

=> ( x – 6 )

=> s = ( x – 6 ) X 5

=> s = (5x – 30) …….(2)

From equation (1) and (2) we get,

=> s = ( x + 6 ) = ( 5x – 30 )

=> x + 6 = 5x – 30

=> 6 + 30 = 5x – x

=> 36 = 4x

=> x = 9

## Therefore,

## speed of boat in still water = 9 km/hr.