charmaine wrote:one day a car rental agency rented 2/3 of its cars, including 3/5 of its cars with CD players. if 3/4 of its cars have CD players, what percentage of the cars that were not rented had CD players ?
a. 10%
b. 35%
c. 45 %
d. 66.7%
e. 90%
This is an EITHER/OR group problem.
Every car EITHER was rented OR was not.
Every car EITHER has a CD player OR does not.
For an EITHER/OR group problem, we can use a GROUP GRID (also known as a double-matrix) to organize the data.
Let R = rented, NR = not rented, CD = CD player, NCD = no CD player.
In the grids below, the entries in any given row or column must add up to the TOTAL of that row or column.
Let the total = the LCM of the denominators in the problem (3, 4, 5) = 60:
Now complete the grid step by step.
Calculate the EASIEST values first.
Rented 2/3 of its cars.
3/4 of its cars have CD players.
Rented 3/5 of its cars with CD players.
Thus, of the 45 cars with CD players, the number rented = (3/5) * 45 = 27, yielding the following grid:
Thus:
(not rented with CD players)/(total not rented) = 18/20 * 100 = 90%.
The correct answer is
E.
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