Question

Sreya can cover a certain distance by walking in 8 hours with 21km/hr speed. Find her speed if she is running and takes 6 hours to cover the same distance.

• A. 25 km/hr
• B. 28 km/hr
• C. 24 km/hr
• D. 30 km/hr

Answer 1

The correct option is B 28 km/hr

Since the distances are the same, time is inversely proportional to speed.

Time for walking : Time for running $=8:6=4:3$

So Speed while walking : Speed while running $=3:4$

$\frac{3}{4}=\frac{21}{x}$ where $x$ is the speed while running

$x=\frac{21\times 4}{3}=28km/hr$