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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 » Thu Aug 20, 2020 7:13 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 » Mon Aug 24, 2020 6:48 am

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BTGModeratorVI wrote: ↑
Thu Aug 20, 2020 7:13 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
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Re: A class contains boys and girls. What is the probability of selecting a boy from a class?

by swerve » Tue Aug 25, 2020 1:11 pm

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BTGModeratorVI wrote: ↑
Thu Aug 20, 2020 7:13 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
Statement 1: the breakdown of boys to girls is not given.
Insufficient\(\Large{\color{red}\chi}\)

Statement 2:
\(3\) boys for every \(4\) girls. So \(3\) boys out of \(7\) total people
Sufficient\(\Large{\color{green}\checkmark}\)

Therefore, B
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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 » Wed Aug 26, 2020 5:34 am

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Your Answer

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B

C

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BTGModeratorVI wrote: ↑
Thu Aug 20, 2020 7:13 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
Kudos for a correct solution.[/quote]

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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