Bluman A.G. Elementary Statistics- A Step By Step Approach

192 Chapter 4 Probability and Counting RulesExample 4–12Travel SurveyIn the travel survey just described, find the probability that a person will travel byairplane over the Thanksgiving holiday.SolutionPE f n 650 325Note: These figures are based on an AAA survey.Example 4–13Distribution of Blood TypesIn a sample of 50 people, 21 had type O blood, 22 had type A blood, 5 had type Bblood, and 2 had type AB blood. Set up a frequency distribution and find the followingprobabilities.a. A person has type O blood.b. A person has type A or type B blood.c. A person has neither type A nor type O blood.d. A person does not have type AB blood.Source: The American Red Cross.SolutionTypeFrequencyA 22B 5AB 2O 21Total 50a. PO f n 2150b. PA or B 2250 550 2750(Add the frequencies of the two classes.)c. Pneither A nor O 550 250 750(Neither A nor O means that a person has either type B or type AB blood.)d. Pnot AB 1 PAB 1 250 4850 2425(Find the probability of not AB by subtracting the probability of type ABfrom 1.)4–12