A schoolboy travelling at 3 km/hr reaches school 28 minutes late, but travelling at 5 km/hr reaches 28 minutes early. What distance does he travel each day to reach school?

A6 km

B8 km

C7 km ✓ Correct

D9 km

Correct answer: (C) 7 km

Explanation

The distance is 7 km.

Late by 28 min and early by 28 min gives a time gap of 56 min = 56/60 hr.

Time gap = D/3 - D/5 = D(2/15).

So D(2/15) = 56/60.

D = (56/60) x (15/2) = 7.

The difference of travel times equals the total lateness plus earliness.

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