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Solution



Given:
    • At Learngood Elementary, one of the students is randomly selected

To find:
    • The probability that the selected student will be a boy

Analysing Statement 1
    • As per the information given in statement 1, there are 480 students in total.
      o However, among those 480 students, we don’t know how many boys and how many girls
    • Therefore, we can’t find the probability of selecting a boy

Hence, statement 1 is not sufficient to answer

Analysing Statement 2
    • As per the information given in statement 2, the ratio of boys to girls is 7:5
      o We can assume the number of boys is 7x and girls 5x
      o Hence, the probability of selecting a boy = \(\frac{7x}{7x + 5x}\) = \(\frac{7}{12}\)
    • So, from statement 2, we can find the probability

Hence, the correct answer is option B.

Answer: B
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Bunuel
If a student is selected at random from Learngood Elementary, what is the probability that the student will be a boy?

(1) There are 480 students at Learngood.
(2) At Learngood, the ratio of boys to girls is 7:5

Target question: What is the probability that the (selected) student will be a boy?

Statement 1: There are 480 students at Learngood.
Since we have no information about the number of boys at the school, statement 1 is NOT SUFFICIENT

Statement 2: At Learngood, the ratio of boys to girls is 7:5
This tells us that, for every 12 children at the school, 7 are boys, and 5 are girls.
In other words, 7/12 of the students at the school are boys, which means P(selected student is a boy) = 7/12
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer: B

Cheers,
Brent
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