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    Question

    A boy is traveling to a destination. If he moves at a

    speed of 20 meters per second, he arrives 20 seconds late. Conversely, if his speed is 40 meters per second, he arrives 10 seconds early. Calculate the distance to his destination in kilometers.
    A 1.2 km Correct Answer Incorrect Answer
    B 1.5 km Correct Answer Incorrect Answer
    C 1.6 km Correct Answer Incorrect Answer
    D 1.8 km Correct Answer Incorrect Answer

    Solution

    Let the distance and time taken by boy to reach his destination if he travels at his usual speed be 'D' metres and 'T' seconds, respectively. Using, distance = speed X time 'D' = 20 X (T + 20) ------ (I) And, 'D' = 40 X (T - 10) --------- (II) From equations (I) and (II) , We have; 20 X (T + 20) = 40 X (T - 10) Or, T + 20 = 2T - 20 Or, 'T' = 40 On putting 'T' = 40 in equation (I) , We have, 'D' = 20 X (40 + 20) = 1,200 metres = 1.2 km 

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