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If a man goes from place A to B at a speed of 12 km/h and return at a speed of 18 km/h, then the average speed for the whole journey is: |
6 km/h 30 km/h $14\frac{2}{5}$km/h 15 km/h |
$14\frac{2}{5}$km/h |
Average speed = \(\frac{2 × S1 × S2 }{S1 + S2}\) = \(\frac{2 × 12 × 18 }{12 + 18}\) = \(\frac{432 }{30}\) = 14\(\frac{2 }{5}\) km/h |
