SK BELLARE
SK BELLARE
8 years ago

If a boy walks from his house to town at a speed of 5 km/hr. he is late by 42 minutes. However if he walks at 6 km/hr. he is late by 5 minutes. What is the distance of town from his house.

A. 12.5 km

B. 18.5 km

C. 15.5 km

D. 21.5 km


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Comments ( 1 )

  1. Kumar Chandan
    Kumar Chandan :
    8 years ago

    Let usual speed was S and usual time was T and distance is D.
    ST = D ------------------------ (1)
    With speed of 5 kmph, he late by 42 min
    Time taken = T + 42/60 = T + 0.7
    So, 5 * (T + 0.7) = D ------------------------- (2)
    Comparing (1) and (2)
    ST = 5 * (T + 0.7)
    ST = 5T + 3.5 ------------------------ (3)
    For 6 kmph, late by 5 min.
    Time taken = T + 5/60 = T + 0.083
    6 * (T + 0.083) = D ----------- (4)
    Equating equation (1) and (4), we get
    ST = 6T + 0.5 -------------- (5)
    Now, (5) - (3)
    ST - ST = 6T + 0.5 - 5T - 3.5
    T = 3
    Required distance,
    5 * (T + 0.7) = D
    D = 15 + 3.5 = 18.5 km

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