SOLUTION: A runner averages 6 kph in the first lap of a race. How fast would she have to run on the second lap in order to average 8 kph for the entire race?

Question 1036055: A runner averages 6 kph in the first lap of a race. How fast would she have to run on the second lap in order to average 8 kph for the entire race?
Answer by fractalier(6550) (Show Source): You can put this solution on YOUR website!
One way to do this is to assume there is 24 km per lap (it is the common multiple of 6 and 8)...
Thus she would take 4 hours to finish that first lap.
She wants to complete 2 laps of 24 km to average 8 kph, so she can take 48/8 = 6 hours total to do that.
She has already run for 4 hours, thus she would need to finish the second 24 km lap in 2 hours, an average of
12 kph
(By the way, it doesn't matter what distance you choose as a lap...)
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