the distance between Delhi and Agra is 200 km . A train travels the first 200 km at a speed of 100 km/h . How fast must the train travel the

Question

the distance between Delhi and Agra is 200 km . A train travels the first 200 km at a speed of 100 km/h . How fast must the train travel the next 100km, so as to average 70km/h for the whole journey​

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Caroline 7 days 2021-09-14T19:53:43+00:00 2 Answers 0 views 0

Answers ( )

    0
    2021-09-14T19:55:11+00:00

    \sf\small\underline\red{Given:-}

    Distance = 100 km

    Speed = 50 km/h

    \sf\small\underline\red{To  \:  \: Find:-}

    To find the average speed we need to use the relation:

    \sf\small\underline\red{using \: formula:-}

    Average speed = Total distance traveled/ Total time taken

    \sf\small\underline\red{Solution:-}

    Let’s find the time taken by train to travel each part of the distance.

    For the first part:

    Distance = 100 km

    Speed = 50 km/h

    Time = Distance/Speed = 100/50 = 2 h

    For the second part:

    Let the speed of the train be ‘s’ km/h

    Distance = 100 km

    Time = Distance/Speed = 100/s

    Now, as we know that:

    Average speed = Total distance traveled/ Total time taken

    where, Average speed = 70 km/h

    Total distance travelled = 200 km

    Total time taken = 2 + 100/s

    Substituting these values in the average speed equation, we get:

    Average speed = Total distance traveled/ Total time taken

    or, 70 = 200/ (2 + 100/s)

    or, 70 × (2 + 100/s) = 200

    or, 140 + 7000/s = 200

    or, 7000/s = 60

    or, s = 7000/60

     = 116.67 \: km.h

    \sf\small\underline\red{Note:-}

    • Therefore, the speed of the train must be 116.67 km/h.

    \huge\mathtt{\fcolorbox{black}{black}{\orange{☯︎Good luck}☯︎}}

    0
    2021-09-14T19:55:13+00:00

    Answer:

    200/100 +100/x =300/70

    Time equal

    2+100/x=30/7

    100/x=30/7-2

    100/x=16/7

    x=7*100/16

    x=7*6.25

    x=43.75 km

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