A car takes 4 hours to reach a destination travelling at the speed of 63 km/h. How long will it take to cover the same distance if the car travells at the speed of 56 km/h? Do these quantities (time and speed) vary directly or inversely? Find the constant of variation.

A car takes 4 hours to reach a destination travelling at the speed of 63 km/h.

Speed = distance / time

Distance = speed × time

Distance it took the car, travelling for 4 hours to a destination at a speed of 63 kilometers per hour would be

4 × 63 = 252 kilometers.

if the car travels at a different speed of 56 kilometers per hour and the distance remains 252 kilometers, the time it takes will be

Time = distance / speed

= 252/56 = 4.5 hours

The time varies inversely with the speed. The more the speed, the lesser the time and the lesser the speed, the more the time.

Let speed = s and let time = t

s varies inversely with t

Introducing constant of inverse variation k, it becomes

s = k/t

When s = 56, t = 4.5

56 = k/4.5

k = 4.5 × 56 =252

This is the distance

Step-by-step explanation: