New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

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

    his speed by 18 km/h after every hour. He reached his destination in 20 hours. If his initial speed was 50 km/h, then what was his average speed in the whole journey?
    A 220 km/h Correct Answer Incorrect Answer
    B 211 km/h Correct Answer Incorrect Answer
    C 221 km/h Correct Answer Incorrect Answer
    D 121 km/h Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Total distance travelled by A = (20/2) × {2 × 50 + (20 – 1) × 18} = 10 × (100 + 342) = 4420 km Required average speed = 4420/20 = 221 km/h

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