Question

The distance between two places is 120kilometre.A car travelling at a certain speed can cover the distance in 2h 30 mins. By how many km per hour should the speed be increased for it to take 30 minutes less to cover the distance?​

Answer 1

Here, distance =120km and time=2hr30min

So, speed = distance/ time

Average speed = 120/ 2.5 because 2hr30min = 2.5 hrs

120/2.5= 48km/h

Now, 2hr30min - 30min = 2hrs

So, 120/2 = 60km/h »»» (60–48)km/h = 12km/h

This is the correct answer according to the question..

Answer 2

If you cover 120km in 2 hrs 30 minutes, your average speed must be 120 / 2.5 = 48 km/hr. Obviously to “do it 30 minutes faster” would be 2 hours flat not 2 hrs 30 minutes. 120km in 2 hours is 120/2 = 60 km per hour.

The difference between the two, 60km and 48 km is 12.

Drive 12KPH faster to cover the same distance in 30 minutes less time..

Ans:- 12 km/h