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:​

in progress 0
Samantha 3 weeks 2021-10-08T05:16:21+00:00 2 Answers 0 views 0

Answers ( )

    0
    2021-10-08T05:17:57+00:00

    Given :

    • 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.

    To Find :-

    • Speed of the boat in still water.

    Solution :-

    Let,

    The distance covered = s.

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

    We know that,

    • Distance = Speed × Time

    Given that,

    • Time taken for downstream in a river = 1 hours.

    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/hr

    Answer :-

    • The speed of the boat in still water is 9 km/hr.
    0
    2021-10-08T05:18:18+00:00

    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?

    According to the question,

    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.

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