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A man, on tour travel first 160 km. at 64 km/hr. and the next 160 km. at 80 km/hr. The average speed for first 320 km. of the tour is ?
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- 35.55 km/hr
- 71.11 km/hr
- 36 km/hr
- 72 km/hr
Correct Option: B
Average speed = 2uv / ( u + v ) km/hr
=(2 x 64 x 80) / (64 + 80) km/hr
= (2 x 64 x 80) / 144 km/hr.
= 71.11 km/hr
