Richa travels from A to B at the speed of 15 km/h, from B to C at 20 km/h, and from C to D at 30 km/h. If AB = BC = CD, then find the Richa's average speed.

A. 19 km/h

B. 17 km/h

C. 18 km/h

D. 20 km/h

Answer: Option D

Solution(By Examveda Team)

$$\eqalign{ & {\text{Distance}} = {\text{ LCM of }}15,\,20,\,30 = 60{\text{ km}} \cr & {\text{Average speed}} = \frac{{{\text{Total distance}}}}{{{\text{Total time}}}} \cr & = \frac{{3 \times 60}}{{4 + 3 + 2}} \cr & = \frac{{180}}{9} \cr & = \boxed{20{\text{ km/h}}} \cr} $$