Question

A police car is ordered to chase a speeding car which is 5 km ahead and is travelling at an average speed of 80 km/h. The police car is running at an average speed of 100 km/h. How long it take for the police car to overtake the speeding car?

Answer 1

The average speed of speeding car is 80 km/h.
The average speed of police car is 100 km/h.
As the police car and the speeding car is moving in the same direction so
Therefore there average speed would be subtracted to get the total speed
= 100lm/hr - 80 km/hr
= 20 km/hr
Therefore the car will travel 20km in 1 hour i.e. 20km in 60 minutes

So, the time taken by car to travel 1km = `(60)/(20)` = 3 minutes

So. time taken by car to cover a distance og 5 km as the speeding car is 5 km ahead 

= `(60)/(20) xx 5`
= 15 minutes.