A class contains boys and girls. What is the probability of selecting

Statement 1: the breakdown of boys to girls is not given
Insufficient

Statement 2:
3 boys for every 4 girls. so 3 boys out of 7 total people
Sufficient

Answer: B

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

vsaketram - the ratio of boys to total number of students will it rather be 3/7

Hence B is sufficient.

I think...B
P(B)=3/7

Answer : B
Second statement is enough to answer the question

MAGOOSH OFFICIAL SOLUTION

Fundamentally, Probability = (desired options)/(total options). The “desired options” are the number of boys and the “total options” is the number of students.

Statement #1: we know here the “total options”, but we don’t know how many of these 35 students are boys. This statement, alone and by itself, is insufficient.

Statement #2: Ignore the information in the first statement. From any ratio among parts, we can calculate the ratio to the whole. If boys are “3 parts” and girls are “4 parts” , so the whole must be 3 + 4 = 7 parts. Thus, the ratio of boys to whole is 3/7 — that’s the probability. Using the properties of ratios, we can answer the prompt question. This statement, alone and by itself, is sufficient.

First not sufficient, second sufficient. Answer = B.

- See more at: https://magoosh.com/gmat/2013/gmat-data- ... JzRXH.dpuf

ration is given for boys and girls then we can find the probabilty that will be 3/3+4=3/7..ans

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