A man on tour travels 160 km by car at 64 km/hr and another 160 km by bus at 80 km/hr. The average speed for the whole journey 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)

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