The time required to drive a fixed distance varies inversely as the speed. It takes 40 hr at a speed of 10 km/h to drive a fixed distance. How long will it take to drive the same distance at a speed of 400 km/h?

Answer

1 hour.

Explanation

The first step is to find the constant of proportionality.

t ∝ s Where t ⇒ time

s ⇒ speed

t = k/s Where k ⇒ constant of proportionality.

40 = k/10

k = 40 * 10

= 400

The formula now becomes;

t = 400/s

For 400 km/h time will be;

t = 400/400

= 1 hour.