If a student is selected at random from Learngood Elementary

[AAPL]

Magoosh

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.

OA B

[Jay@ManhattanReview]

Magoosh

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.

OA B

Let's take each statement one by one.

1) There are 480 students at Learngood.

No information about how many boys and girls there in the school. Can't get the answer. Insufficient.

2) At Learngood, the ratio of boys to girls is 7 : 5.

Say there are 7x boys and 5x girls, where x = any positive integer

Probability that the student will be a boy, if a student is selected at random = 7x/(7x + 5x) = 7/12. Sufficient

The correct answer: B

Hope this helps!

-Jay
_________________
Manhattan Review GMAT Prep

Locations: GMAT Manhattan | GRE Prep Courses Boston | ACT Prep Courses San Francisco | Seattle IELTS Tutoring | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.