GMAT TIGER wrote:
shobuj40 wrote:
A certain military vehicle can run on pure Fuel X, pure Fuel Y, or any mixture of X and Y. Fuel X costs $3 per gallon; the vehicle can go 20 miles on a gallon of Fuel X. In contrast, Fuel Y costs $5 per gallon, but the vehicle can go 40 miles on a gallon of Fuel Y. What is the cost per gallon of the fuel mixture currently in the vehicle’s tank?
1) Using fuel currently in its tank, the vehicle burned 8 gallons to cover 200 miles.
2) The vehicle can cover 7 and 1/7 miles for every dollar of fuel currently in its tank
D.
1) 20x + 40 (8-x) = 200.
x = Fuel x and y = 8-x
x = 6
y = 2. suff.
2) 20/3 (a) + 40/5 (1-a) = 50/7
a = 9/14
1-a = 5/14
fraction of $ for fuel x + fraction of $ for fuel y = 1
a = fraction of $ for fuel x
1-a = fraction of $ for fuel y
suff...
Hi GMAT-mate,
To further the solution to find what is needed, won't the equation be as below for statement 2-
9/14 * 3 + 5/14 * 5 = 26/7
For statement 1, the answer is
(6*3+2*5)/8 = 28/8
The 2 figures aren't matching. In GMAT-DS, the solution has to be consistent for each statements if the answer is D.
Have I done some mistake.