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If a man swims 4 miters upstream at 1 mph and back downstream to the same point at 4 mph, what is his average speed?

If a man swims 4 miters upstream at 1 mph and back downstream to the same point at 4 mph, what is his average speed? Correct Answer 1.6 mph

Let towards upstream he swims at v1 mph and towards downstream he swims at v2 mph . '. v1 = 1 and v2 = 4 Now, his average speed = 21v1 + 1v2 = 211 + 14 = 21 + 14 = 254 = 254 = 2 × 43 = 85 = 1.6 mph[Rule of harmonic mean ]Total 5 mph swims 8 mitres  58 1.6 mph 53030 ×

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