A jogger desires to run a certain course in 1/4 less time than she usually takes. By what percent must she increase her average running speed to accomplish this goal?

Asked by  | 29th Sep, 2012, 11:01: AM

Expert Answer:

Let the jogger usually takes t minutes to cover a distance of x m.

So, his usual speed is x/t m/s.

 

Since, he desires to take 1/4 less time than he takes usually so, he desires to take 3t/4 minutes to cover x m.

In this case his speed has to be x/(3t/4) = 4x/3t m/s.

 

The speed that has to increase to desired the Jogger's goal = (4x/3t - x/t) m/s = x/3t m/s.

So, the percentage of speed the Jogger needs to increase = increase speed/original speed × 100 = 1/3 × 100 = 33.33 % (approx)

Answered by  | 29th Sep, 2012, 02:42: PM

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