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Cars at trade show.

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Cars at trade show.

by rahulvsd » Sun Nov 06, 2011 5:28 am
For a trade show, two different cars are selected randomly from a lot of 20 cars. If all the cars on the lot are either sedans or convertibles, is the probability that both cars selected will be sedans greater than 3/4?

1. At least three-fourths of the cars are sedans.
2. The probability that both of the cars selected will be convertibles is less than 1/20.

[spoiler]OA: E[/spoiler][/spoiler]
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Source: — Data Sufficiency |
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by shankar.ashwin » Sun Nov 06, 2011 5:50 am
Total 20 cars.

Is P( Both sedans) > 3/4 ?

Even before looking at options, you can do this small math to see when the Prob would be > 3/4.

S/20 * (S-1)/19 > 3/4. Where S is N(sedans)

S*(S-1) > 285 (or) S> 18.

Now Statement 1:

N(Sedans) > 15 - Insuff

Statement 2:

You know N(S) should be >18. Just check for N(C) = 3.

3/20 * 2/19 = 3/190 which is still < than 1/20.

Even together, we can't say. E IMO
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