Murphy and Cooper are having the same amount of petrol in the petrol tanks of their respective cars. Murphy can drive for four hours with that amount whole Cooper can drive for five hours.
They both starts together and keep driving for a few hours. After some time, they find that the amount of petrol remaining in one car is four times that of the other car.
Using all these facts, can you find out how long they drove their cars?	Select.
A) 2 3/4 hours.
B) 3 3/4 hours.
C) 4 3/4 hours.
D) 5 3/4 hours.
E) 6 3/4 hours.
Solution:   3 3/4 hours   Explanation:   Suppose that the amount of petrol in each of the cars in the beginning was M.   Now, suppose that they drove for X hours.   In that case, the amount of petrol used by one car in X hours will be = M*X /4   The amount of petrol used by the other car will be = M*X/5   Therefore, the petrol left in one car = M - M*X / 4   Petrol left in the other car = M - M*X / 5   Now, according to the question,   M - M*X / 5 = 4 (M - M*X / 4)   =&gt; X = 15 / 4 = 3 3/4 hours.   Therefore Murphy and Cooper drove for 3 3/4 hours.   Answer 3 3/4 hours.
<result>B</result>
Murphy and Cooper are having the same amount of petrol in the petrol tanks of their respective cars. Murphy can drive for four hours with that amount whole Cooper can drive for five hours.
They both starts together and keep driving for a few hours. After some time, they find that the amount of petrol remaining in one car is four times that of the other car.
Using all these facts, can you find out how long they drove their cars?