The General Multiplication Rule

It is known that a certain disease occurs in 5% of a large population. A test for the disease has a positive result 90% of the time for people with the disease. What is the probability a randomly selected person has the disease and tests positive for the disease?

• O.95

• 0.85

• 0.055

• 0.045

At a large high school, 15% of the students drive to school. Of the students that drive to school, 80% are seniors. What is the probability a randomly selected student drives to school and is a senior?

• 0.12

• 0.19

• 0.65

• 0.95

At a local high school, 30% of the students are enrolled in Chemistry. Of the students enrolled in Chemistry, 60% are also enrolled in Algebra 2. Of the students not enrolled in Chemistry, 20% are enrolled in Algebra 2. What is th probability that a randomly chosen student from this high school is enrolled in algebra 2?

• 0.18

• 0.80

• 0.40

• 0.32

A fast food restaurant sells meals in three different sizes. Based on sales from the last month, 20% of the customers purchase the small size, 30% purchase the medium size, and 50% purchase the large size. Of the customers that purchase the small size, 10% also purchase a soft drink. Of the customers that purchase the medium size, 20% also purchase a diet soft drink. Of the customers that purchase the large size, 40% also purchase a diet soft drink. Based on people that buy one of these type of meals, what is the probability that the customer purchases a soft drink?

• 0.23

• 0.30

• 0.28

• 0.70

Assume a randomly chosen battery has a probability of 0.8 of working. A remote control requires two working batteries in order to work. What is the probability a remote control will work if two randomly chosen batteries are put into a remote control?

• 0.84

• 0.64

• 0.36

• 0.16