4.3  The Addition Rules for Probability

1. At a particular school with 200 male students, 58 play football, 40

play basketball, and 8 play both. What is the probability that a

randomly selected male student plays neither sport?.

2. A furniture store decides to select a month for its annual sale.

Find the probability that it will be April or May. Assume that all

months have equal probability of being selected.

3. An urn contains 6 red balls, 2 green balls, 1 blue ball, and 1 white

ball. If a ball is drawn, find the probability of getting a red or a

white ball.

4. A grocery store employs cashiers, stock clerks, and deli personnel.

The distribution of employees according to marital status is shown

here.

Marital Status / Cashiers / Stock
clerks / Deli personnel
Married / 8 / 12 / 3
Not Married / 5 / 15 / 2

If an employee is selected at random, find these probabilities:

i)  the employee is a stock clerk or married

ii)  the employee is not married

iii)  the employee is a cashier or is not married.

5. At a used-book sale, 100 books are adult books and 160 are

children’s books. Seventy of the adult books are nonfiction while 60

of the children’s books are nonfiction. If a book is selected at

random, find the probability that it is

i)  fiction

ii)  not a children’s nonfiction

iii)  an adult book or a children’s nonfiction.

6. One white die and one black die are rolled. Find the probability that

the white die shows a number smaller than 3 or the sum of the

dice is greater than 9.

7. A pair of dice is rolled. Event T is defined as the occurrence of a

“total of 10 or 11”, and event D is the occurrence of “doubles”. Find

P(T or D).