# I really do not get how this problem help?

An automobile engine can run on a mixture of gasoline and a substitute fuel. If gas costs $3.35 per gallon and the substitute fuel costs $2 per gallon, what percent of a mixture must be substitute fuel to bring the cost down to $3.08 per gallon?

### 4 Answers

- oldprofLv 71 month agoBest Answer
An automobile engine can run on a mixture of gasoline and a substitute fuel. If gas costs G = $3.35 per gallon and the substitute fuel costs S = $2 per gallon, what percent of a mixture must be substitute fuel to bring the cost down to Cavg = $3.08 per gallon?

This is a weighted average problem, where Cavg = aG + bS = (1 - x)G + xS and a and b are the weights. So you solve for x, then you have 1 - x and the percentage of each fuel in the mixture.

Cavg = G - xG + xS = G + x(S - G); and (Cavg - G)/(S - G) = x. ANS you can do the math.

- Anonymous1 month ago
WRONG FORUM. Go to Homework Help in the Education category.

- Jay PLv 71 month ago
Your "car" problem is actually a math problem and should be relocated to the homework help section, not the Cars & Transportation section...