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A class contains boys and girls. What is the probability of selecting a boy from a class?

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A class contains boys and girls. What is the probability of selecting a boy from a class?

by BTGModeratorVI » Sat May 16, 2020 7:35 am

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A class contains boys and girls. What is the probability of selecting a boy from a class?

(1) There are 35 students in the class
(2) The ratio of boys to girls is 3:4

Answer: B
Source: Magoosh
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Source: — Data Sufficiency |

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Re: A class contains boys and girls. What is the probability of selecting a boy from a class?

by Brent@GMATPrepNow » Sun May 17, 2020 8:10 am

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BTGModeratorVI wrote: ↑
Sat May 16, 2020 7:35 am
 A class contains boys and girls. What is the probability of selecting a boy from a class?

(1) There are 35 students in the class
(2) The ratio of boys to girls is 3:4

Answer: B
Source: Magoosh
Target question: What is the probability of selecting a boy from a class?

Statement 1: There are 35 students in the class
In order to determine the probability of selecting a boy, we need to know what fraction of the 35 students are boys.
So, as it stands, statement 1 is NOT SUFFICIENT

Statement 2: The ratio of boys to girls is 3:4
This means that, out of every 7 children, 3 of them are boys, and 4 of them are girls.
So, P(selecting a boy) = 3/7
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer: B

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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