Walking 3 upon 4 of his usual speed , a student is 10 minutes late to school . Find his usual time to cover the distance .
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Let the speed be x m per min
Recall that time = (distane)/(speed)
Time taken with speed x m/min = d/x → (1)
3/4 th of the speed is (3x/4) m per min
Time taken when speed is reduced = d/(3x/4) = 4d/3x
Given difference in the time is 10 minutes
(4d/3x) − (d/x) = 10
⇒ (d/3x) = 10
∴ (d/x) = 30 minutes
Thus time taken with the usual speed is 30 minutes.
Recall that time = (distane)/(speed)
Time taken with speed x m/min = d/x → (1)
3/4 th of the speed is (3x/4) m per min
Time taken when speed is reduced = d/(3x/4) = 4d/3x
Given difference in the time is 10 minutes
(4d/3x) − (d/x) = 10
⇒ (d/3x) = 10
∴ (d/x) = 30 minutes
Thus time taken with the usual speed is 30 minutes.
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