Bunuel
Competition Mode Question
Dealership A and Dealership B both sell cars and trucks. If the ratio of cars to trucks each dealership sold in the last month is the same for both dealerships, did Dealership A sell the same number of cars and trucks last month?
(1) The number of trucks sold by Dealership B was three times the number of cars sold by Dealership A.
(2) The number of cars sold by Dealership B was equal to the number of trucks sold by Dealership A plus twice the number of cars sold by Dealership A.
Are You Up For the Challenge: 700 Level QuestionsSay A sells c cars and t trucks.
Ratio of cars:trucks = c:t
B sells cars:trucks in the ratio c:t too.
We need to find if c = t or if c/t = 1?
(1) The number of trucks sold by Dealership B was three times the number of cars sold by Dealership A.
Trucks sold by B = 3c
Not sufficient.
(2) The number of cars sold by Dealership B was equal to the number of trucks sold by Dealership A plus twice the number of cars sold by Dealership A.
Cars sold by B = t + 2c
Not sufficient.
Using both, (t + 2c)/3c = c/t (Ratio of cars/trucks for B)
\(t^2 + 2ct = 3c^2\)
Divide by t^2 to get \(3\frac{c^2}{t^2} - 2(\frac{c}{t}) - 1 = 0\) (assume c/t = x)
\(3x^2 - 2x - 1 = 0\)
\((3x + 1)(x - 1) = 0\)
Since x cannot be negative (number of cars and trucks sold both must be positive), x = 1 i.e. c/t = 1
Sufficient. Answer (C)
For more on how to solve quadratic equations, check:
https://www.gmatclub.com/forum/veritas-prep-resource-links-no-longer-available-399979.html#/2013/1 ... equations/