1. Discrete Math Section 16.4 Use combinations to solve probability Problems A committee of three is to selected from 3 girls and 2 boys. What is the probability of selecting 2 girls and one boy at random? P(BGG) = (2/5)(3/4)(2/3) = 1/5 P(GGB) = (3/5)(2/4)(2/3) = 1/5 P(GBG) = (3/5)(2/4)(2/3) = 1/5 1/5 + 1/5 + 1/5 = 3/5 2 nd method Probability = 3 C 2 2 C 1 _________ = (3)(2) = 3/5 5 C 3 10

2. example Five marbles are chosen at random from a bag containing 4 white, 3 green and 5 black marbles. What is the probability of choosing 2 white, 1 green, and 2 black marbles?

3. example A carton contains 200 batteries, of which 3 are defective. If a random sample of 5 batteries is chosen, what is the probability that at least one of them is defective? (Calculate the probability that none are defective and use Complement Principle: 1 – P(not D) )

4. assignment Page 621 Problems 3,6,8,10,16,19,20