2.8 Compound Events

Ex 1 There are two boxes each containing 4 balls. Box A has 2 blue and 2 green. Box B has 3 red and 1 white. What is the probability that you draw a green ball from box A and a white ball from box B?

Ex 2 You are rolling a die and flipping a coin. What is the probability that you get tails and a 3 at the same time?

Both of these examples exhibit independent probabilities, where two events occur at the same time that have no impact on each other. If A and B are indepedent events, then

Ex 3 A hat contains 5 red and 3 blue tickets. One ticket is randomly chosen and then another ticket is randomly chosen. What is the chance that the second ticket is red?

This is an example of a dependent probability. The probability of the second event is dependent on the first event. is the formula we use here. P(B/A) is read as P of B given A.

Ex 4 A hat contains tickets labelled with numbers from 1 to 20. What is the probability that 3 tickets are drawn without replacing them in the hat are all prime numbers?

p. 471#1-6

p.473#1-4

p.474#1-9