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3 years ago

10

John runs for 10 mins at a uniform speed 9kn/h. At what speed should he run for the next 20mins so that theaverage speed comes t

o 12km/h.

1 answer:

kolbaska11 [484]3 years ago

4 0

Answer:

13.5 km/h

Explanation:

John runs for 10 min at 9 km/h, then 20 min at v. He will have run a total of 30 min at 12 km/h.

Therefore:

(30 min) (12 km/h) = (10 min) (9 km/h) + (20 min) v

v = 13.5 km/h

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