Question

A cheetah runs 4 times faster than a human. If the cheetah has given the human a start of 90 m, what should be the distance of the running post so that the cheetah and the human can reach it at the same time?

• A. 90 m
• B. 100 m
• C. 80 m
• D. 150 m
• E. 120 m

Answer 1

The correct option is E

120 m

Ratio of speed of cheetah and human = 4:1

From the ratio 4:1 we conclude that in a race of 4 m, cheetah gains 3 m more than human.

3 m are being gained by cheetah in a race of 4 m

1 m is being gained by cheetah in a race of $\frac{4}{3}$.

90 m gained by cheetah in a race of = $\frac{4}{3}\times 90=120m$

So, both cheetah and human will reach at the same time when the post will be 120 m.