ii. Rahim travels 600 km to his home partly by train and partly by car. He takes 8 hours if he travels 120 km by train and rest by car.

Question

ii. Rahim travels 600 km to his home partly by train and partly by car. He takes 8 hours
if he travels 120 km by train and rest by car. He takes 20 minutes more if he travels
200 km by train and rest by car. Find the speed of the train and the car

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Josie 7 months 2021-10-13T18:11:20+00:00 1 Answer 0 views 0

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    0
    2021-10-13T18:12:41+00:00

    solution;

    Case 1:

    —————

    Total distance = 600km

    Distance covered by train: 120km

    Time taken by train: (120)/x km/h  [Let ‘x’ be the speed of the train]

    Distance covered by car: (600-120) = 480km

    Time taken by car: (480)/y km/h [Let ‘y’ be the speed of the car]

    Total time taken: (120)/x + (480)/y = 8 or (10)/x + (40)/y = 2/3 or (30)/x + (120)/y = 2 …… (1)

    Case II:

    ————–

    Total distance covered by train: 200 km

    Total time taken by train: (200)/x km/h

    Total distance covered by car: (600-200) = 400 km

    Total time taken by car: (400)/y km/h

    Total time taken: 8(20/60) = (25)/3

    (200)/x + (400)/y = (25)/3

    or (600)x + (1200)/y = 25 ….. (2)

    Let 1/x be u and 1/y be v …. (3)

    Equations are then:

    600u + 1200v = 25

    30u + 120v = 2

    Multiplying equation (1) by 20 and subtracting the equations we get:

    1200v = 15 ; v = (15)/(1200)

    Since, 1/y = v

    y = (1200)/3 = 80

    y = 80 km/h

    So, the speed of the car is 80 km/h.

    Hence the speed of the train,

    Multiplying equation (1) by 10 and subtracting equations we get:

    300u = 5

    u = 5/(300)

    Since, 1/x = u

    x = (300)/5 ; x = 60

    x = 60 km/h

    So, the speed of the train is 60 km/h.

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