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# At least 10 cars have tinting window and fog light. 40% cars which hav

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Math Revolution GMAT Instructor
Joined: 16 Aug 2015
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At least 10 cars have tinting window and fog light. 40% cars which hav [#permalink]

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14 Jun 2016, 08:06
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Question Stats:

55% (02:30) correct 45% (02:36) wrong based on 69 sessions

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At least 10 cars have tinting window and fog light. 40% cars which have tinting windows also have fog light, is the number of the cars with tinting windows larger than that of the cars with the fog light?
1) 80% cars which have fog light also have tinting windows
2) 52 cars have tinting windows or fog light or both

*An answer will be posted in 2 days.
[Reveal] Spoiler: OA

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Re: At least 10 cars have tinting window and fog light. 40% cars which hav [#permalink]

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14 Jun 2016, 08:32
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Expert's post
MathRevolution wrote:
At least 10 cars have tinting window and fog light. 40% cars which have tinting windows also have fog light, is the number of the cars with tinting windows larger than that of the cars with the fog light?
1) 80% cars which have fog light also have tinting windows
2) 52 cars have tinting windows or fog light or both

*An answer will be posted in 2 days.
.....

cars with tinting window = $$C_t....$$
and cars with fog light =$$C_f....$$
and cars with both = $$C_b....$$
now $$0.4 C_t = C_b...$$

lets see the statements ..

1) 80% cars which have fog light also have tinting windows
so $$0.8 C_f = C_b....$$
so $$0.8 C_f = 0.4 C_t.................2C_f = C_t$$
Suff..

2) 52 cars have tinting windows or fog light or both
Just gives total number of cars
Insuff

A
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At least 10 cars have tinting window and fog light. 40% cars which hav [#permalink]

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14 Jun 2016, 12:03
MathRevolution wrote:
At least 10 cars have tinting window and fog light. 40% cars which have tinting windows also have fog light, is the number of the cars with tinting windows larger than that of the cars with the fog light?
1) 80% cars which have fog light also have tinting windows
2) 52 cars have tinting windows or fog light or both

*An answer will be posted in 2 days.

1) 40% cars which have tinting windows=80% cars which have fog light=cars have tinting window and fog light, So the number of cars which have tinting windows is definitely larger,Sufficient

2) No particular breakdown about cars have tinting windows or fog light or both,Insuficient

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Re: At least 10 cars have tinting window and fog light. 40% cars which hav [#permalink]

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16 Jun 2016, 19:24
If we were to solve this question with our trick, we should observe if one of conditions include ratio. If one of conditions contains ratio, then the condition with ratio has 90% of chance to become the answer. Since the condition 1) has ratio, the correct answer is A.

- Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.
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Re: At least 10 cars have tinting window and fog light. 40% cars which hav [#permalink]

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22 Dec 2017, 12:16
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: At least 10 cars have tinting window and fog light. 40% cars which hav   [#permalink] 22 Dec 2017, 12:16
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