Question

    A was travelling from point X to point Y. He increased

    his speed by 4 km/h after every hour. He reached his destination in 8 hours. If his initial speed was 40 km/h, then what was his average speed in the whole journey?
    A 50 km/h Correct Answer Incorrect Answer
    B 24 km/h Correct Answer Incorrect Answer
    C 54 km/h Correct Answer Incorrect Answer
    D 44 km/h Correct Answer Incorrect Answer

    Solution

    Total distance travelled by A = (8/2) × {2 × 40 + (8 – 1) × 4} = 4 × (80 + 28) = 432 km Required average speed = 432/8 = 54 km/h

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