Percent question

Question

How many gallons of 5% ethanol gasoline must be mixed with how many gallons of 12% ethanol gasoline to get 700 gallons of 10% ethanol?

Answer 1

Let F = gal of 5% and T = gal of 12%

 

Total amt = F + T = 700

 

Amt of EtOH in 5% = .05F and in 12% = .12T

Amt in 700 gal = .1 * 700 = 70

 

Therefore .05F + .12T = 70

Multiply by 100

5F + 12T = 7000

 

Multiply the first equation by 5

5F + 5T = 3500

 

Subtract

7T = 3500

T = 500

F = 200

 

You should take these answers and make sure they solve the problem as stated.