Question

The total distance between two stations is $570$ km out of which , $224$ km is covered at $56$ km/hr, $210$ km is covered at $70$ km/hr and remaining is covered in $2$ hours. Find the average speed during the whole journey.

• A. $14\frac{1}{3}$ km/hr
• B. $52\frac{1}{3}$ km/hr
• C. $75\frac{1}{3}$ km/hr
• D. $63\frac{1}{3}$ km/hr

Answer 1

The correct option is D $63\frac{1}{3}$ km/hr

Speed $=\frac{Distance}{Time}$

Average Speed $=\frac{TotalDistanceTravelled}{TotalTimeTaken}$

Since $224$ km is covered at $56$ km/hr, Time$1=\frac{Distance}{Speed}=\frac{224}{56}=4$ hr

And since another $210$ km is covered at $70$ km/hr, Time$2=\frac{Distance}{Speed}=\frac{210}{70}=3$ hr

Given, TIme 3 $=2$ hrs

So, total time taken $=4+3+2=9$ hrs

Hence, Average speed $=\frac{570}{9}=63\frac{1}{3}$ km/hr