SOLUTION: After a rise in the price of petrol, the driven mileage dropped down by 6.7%. However the fuel cost increased by 4.5%. By what percentage did the petrol price rise?

Algebra ->  Percentages: Solvers, Trainers, Word Problems and pie charts -> SOLUTION: After a rise in the price of petrol, the driven mileage dropped down by 6.7%. However the fuel cost increased by 4.5%. By what percentage did the petrol price rise?      Log On


   

Question 398066: After a rise in the price of petrol, the driven mileage dropped down by 6.7%. However the fuel cost increased by 4.5%. By what percentage did the petrol price rise?
Answer by Tatiana_Stebko(1539) About Me  (Show Source):
You can put this solution on YOUR website!
if the driven mileage before rise is D, then after rise it will be 0.933*D
If the fuel cost before rice is C, then after rise it will be 1.045*C
So the petrol price before rise is p=C%2FD
the petrol price after rise is P=%281.045C%29%2F%280.933D%29=1.12%2A%28C%2FD%29
so percentage the petrol price rise is %28%28P%2Fp%29-1%29%2A100%25
%28%281.12%2A%28C%2FD%29%29%2F%28C%2FD%29-1%29%2A100=12%