A man on tour travels first 160 km at 64 km/hr and the next 160 km at 80 km/hr. The average speed for the first 320 km of the tour is:

A. 35.55 km/hr

B. 36 km/hr

C. 71.11 km/hr

D. 71 km/hr

Answer: Option C

Solution(By Examveda Team)

$$\eqalign{ & {\text{Total}}\,{\text{time}}\,{\text{taken}} \cr & = \left( {\frac{{160}}{{64}} + \frac{{160}}{{80}}} \right)hrs \cr & = \frac{9}{2}\,hrs \cr & \therefore {\text{Average}}\,{\text{speed}} \cr & = \left( {320 \times \frac{2}{9}} \right)\,{\text{km/hr}} \cr & = 71.11\,{\text{km/hr}} \cr} $$