A man on tour travels the first 320 km at 64 kmph and the rest at 80 kmph. The average speed for the entire 640 km is

A35.55 kmph

B36 kmph

C71.11 kmph ✓ Correct

D71 kmph

Correct answer: (C) 71.11 kmph

Explanation

The average speed is 71.11 kmph.

Time for first 320 km = 320/64 = 5 hours.

Time for next 320 km = 320/80 = 4 hours.

Total time = 5 + 4 = 9 hours for 640 km.

Average speed = total distance / total time = 640/9.

640/9 = 71.11 kmph.

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