Question

Please help i need this done in 5 mins

Answer 1

0.233 or
`(7)/(30)`

Explanation:

Pre-Solving

We are given that 12 people have a brother and a sister, 7 people have a sister but don't have a brother, 3 have a brother but don't have a sister, and 8 don't have either.

We want to find the probability that a random student has a sister but doesn't have a brother.

Recall that probability is
`( favorable outcomes)/(total outcomes)`

So, we have 7 favorable outcomes (7 people that have a sister but don't have a brother), and when we add the total number of people together, we get 30 (the total number of people surveyed, aka our total outcomes).

Solving

Divide 7 by 30.

`(7)/(30)`

We can simplify this:

0.233