Question

    A motor-cycle covers 60 km with a speed of 20 km/hr.

    find the speed of the motor-cycle for the next 60 km journey so that the average speed of the whole journey will be 30 km/hr.
    A 50 km/hr Correct Answer Incorrect Answer
    B 26 km/hr Correct Answer Incorrect Answer
    C 20 km/hr Correct Answer Incorrect Answer
    D 60 km/hr Correct Answer Incorrect Answer

    Solution

    ATQ, First 60 km is traveled at 20 km/hr, So, time taken = 60 ÷ 20 = 3 hours. Total distance = 120 km, and average speed needed = 30 km/hr. Total time required = 120 ÷ 30 = 4 hours. Time left for the next 60 km = 4 - 3 = 1 hour. Speed required for the next 60 km = 60 ÷ 1 = 60 km/hr. Therefore, the motorcycle must travel the next 60 km at 60 km/hr. 

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