Question

Bob just filled his car's gas tank with 20 gallons of gasohol, a mixture consisting of 5% ethanol and 95% gasoline. If his car runs best on a mixture consisting of 10% ethanol and 90% gasoline, how many gallons of ethanol must he add into the gas tank for his car to achieve optimum performance?A. 9/10B. 1C. 10/9D. 20/19E. 2

Answer 1

Answer:

C. 10/9 gallons

Explanation:

Given that

V= 20 gallons

Volume of ethanol = 5% of V = 0.05 x 20 = 1 gallons

Volume of the gasoline = 95 % of V = 19 gallons

Lets take x gallons of ethanol is added to achieve optimum performance.

(1+x)/(20+x) = 10 %

(1+x)/(20+x) =0.1

1+ x = 0.1 ( 20+ x)

1+ x = 2 + 0.1 x

1 = 0.9 x

x= 10 /9  gallons

So the option C is correct.

C. 10/9 gallons