Alpha and Beta have same amount of petrol in their respective cars. Alpha can drive for 4 hours whereas Beta can drive for 5 hours with the amount of petrol left.
Both of them start driving at the same time. After a few hours, they find out that the amount of petrol remaining in one of the cars is four times the other car.
Can you calculate for how long did they drive the cars?
3 3/4 hours
Assume that the initial amount of petrol in each of the petrol tanks be P.
Now, let us assume that they drove for H hours.
In that case, the amount of petrol used by one car in H hours will be = P*H /4
The amount of petrol used by the other car will be = P*H/5
Therefore, the petrol left in one car = P - P*H / 4
Petrol left in the other car = P - P*H / 5
Now, according to the question,
P - P*H / 5 = 4 (P - P*H / 4)
=> H = 15 / 4 = 3 3/4 hours.
