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At a car dealership, 10% of all cars are red and have heated
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02 Apr 2020, 08:07
02 Apr 2020, 08:07
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At a car dealership, 10% of all cars are red and have heated seats, and 75% of cars without heated seats are red. If 40% of all of the cars are red, what percent of the cars have heated seats?
(A) 25%
(B) 40%
(C) 60%
(D) 75%
(E) 85%
Kudos for the right answer and explanation
(A) 25%
(B) 40%
(C) 60%
(D) 75%
(E) 85%
Kudos for the right answer and explanation
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: At a car dealership, 10% of all cars are red and have heated
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02 Apr 2020, 09:19
02 Apr 2020, 09:19
Carcass wrote:
At a car dealership, 10% of all cars are red and have heated seats, and 75% of cars without heated seats are red. If 40% of all of the cars are red, what percent of the cars have heated seats?
(A) 25%
(B) 40%
(C) 60%
(D) 75%
(E) 85%
Kudos for the right answer and explanation
(A) 25%
(B) 40%
(C) 60%
(D) 75%
(E) 85%
Kudos for the right answer and explanation
Time for the Double Matrix Method!
This technique can be used for most questions featuring a population in which each member has two characteristics associated with it (aka overlapping sets questions)..
Here, we have a population of cars, and the two characteristics are:
- red or not red
- heated seats or no heated seats
From the given information we can set up our diagram as follows:
Notice that we had to assign a variable (x) to the total number of cars with unheated seats
Since of the two boxes in the top row must add to 40, we can write: 10 + 0.75x = 40
When we solve this equation we get x = 40
If 40 of the 100 cars DON'T have heated seats, then the remaining 60 cars must have heated seats:
Answer: C
This question type is VERY COMMON on the GRE, so be sure to master the technique.
To learn more about the Double Matrix Method, watch this video:
gmatclubot
Re: At a car dealership, 10% of all cars are red and have heated [#permalink]
02 Apr 2020, 09:19
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