In a class 30 of students, 22 have a brother and 25 have a sister. There are 2 students who do not have any siblings. What is the probability that a student chosen randomly from the class does not have a sister?

Guest Mar 15, 2020

#1**+1 **

You should do this with a Venn diagram.

Two overlapping circles inside a rectangle

There are 2 with no siblings that leaves 28 with a brother or a sister or both.

Let x be the number with both.

22 have a brother so 22-x have a brother but no sister.

25 have a sister so 25-x have a sister but no brother

so we have 22-x + x + 25-x = 28

Solve that, find x

Draw the vent diagram properly.

Find the desired probability.

Melody Mar 15, 2020