Question
A was travelling from point X to point Y. He increased
his speed by 8 km/h after every hour. He reached his destination in 12 hours. If his initial speed was 20 km/h, then what was his average speed in the whole journey?Solution
Total distance travelled by A = (12/2) × {2 × 20 + (12 – 1) × 8} = 5 × (40 + 88) = 768 km Required average speed = 768/12 = 64 km/h
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