13.5 Conditional Probability Find the probability of an event given the occurrence of another event.

Conditional Probability The probability of an event under the condition that some preceding event has occurred. 𝑃 𝐴 𝐵 = 𝑃(𝐴 𝑎𝑛𝑑 𝐵) 𝑃(𝐵) 𝑤ℎ𝑒𝑟𝑒 𝑃(𝐵)≠0 1) Vanessa tosses three coins. What is the probability that she has tossed 2 heads, given that she has tossed at least 1 head?

2) The table below provides some information about the ages of the first 42 US presidents at inauguration and their birth states. What is the probability that a president was inaugurated at the age of 60 years or older, given that the president was born in Virginia? Birth State Under 60 60 and Over Virginia 6 2 All other 26 8

3) A 20 sided die has the numerals 1 through 20 on its faces 3) A 20 sided die has the numerals 1 through 20 on its faces. The die is rolled once, and the number on the top face is recorded. What is the probability that the number is a multiple of 3 if it is known that it is odd? 4) Kylie is conducting a survey of families with two pets. The pets could be 2 cats, 2 dogs or one of each. If a family is selected at random, what is the probability that the family will have exactly 2 cats if the second pet is a cat?

Guided Practice P871 4-12