### Distance between two stations A and B is 778km. A train covers the journey from A to B at 84km per hour and returns back to A with a uniform speed of 56km per hour. Find the average speed of train during the whole journey.

**A.** 60 km/hr

**B.** 30.5 km/hr

**C.** 57 km/hr

**D.** 67.2 km/hr

## Show Answer

###
Answer-D
Solution-

__Solution(By Apex Team)__

$\begin{array}{l}\text{Average speed}\\
=\frac{2xy}{x+y}\mathrm{~km}/\mathrm{hr}\\
=\frac{2\times84\times56}{84+56}\mathrm{~km}/\mathrm{hr}\\
=\frac{2\times84\times56}{140}\mathrm{~km}/\mathrm{hr}\\
=67.2\mathrm{~km}/\mathrm{hr}\end{array}$