Algebra 2b
Name:
Probability Practice
1. Real estate ads suggest that 64% of homes for sale have a garage, 21% have
swimming pools, and 17% have both features. What is the probability that a home
for sale has
a. A pool or garage?
b. Neither a pool nor a garage?
c. A pool but no garage?
2. Suppose that 46% of families living in a certain country own a car and 18% own an
SUV. From this data, Mr. Fedderman concludes, “64% of families own either a car or
an SUV.” What is wrong with Mr. F’s reasoning?
3. Traffic checks on a certain stretch of highway suggest that 60% of drivers are
speeding there. Since 0.6(0.6) = 0.36, Mr. Fedderman concludes that there’s a 36%
probability that two vehicles in a row are speeding. What is wrong with Mr. F’s
reasoning?
4. Suppose the probability that Student A gets a C in math class is 0.4 and the
probability that Student B gets a C in math class is 0.1. Are these events
independent?
5. Use the information from question 4 to determine the probability that Student A or
Student B gets a C in math class.
Continued!
6. You roll a fair die three times. Find each probability.
a. You roll all 6’s
b. You roll all odd numbers
c. None of your rolls gets a number divisible by 3
d. You roll at least one 5
e. The numbers you roll are not all 5’s
7. A consumer organization estimates that over a one-year period 17% of cars will
need to be repaired once, 7% will need repairs twice, and 4% will require three or
more repairs. A car is chosen at random. Find each probability.
a. The car will need no repairs
b. The car will need no more than one repair
c. The car will need at least one repair
8. Use the information from question 7. Suppose you own two cars. Find each
probability.
a. Neither will need repair
b. Both will need repair
c. At least one will need repair
9. What assumption do you have to make to answer question 8? Is that assumption
reasonable?