Unit 8 Section 8-5

8-5: z Test for a Proportion  A hypothesis test involving a population proportion can be considered a binomial experiment.  There are two outcomes  Recall…  μ = np  σ= √npq 

 Proportions also involve finding a z-score  Recall: Test value = (Observed Value)-(expected value) Standard error  Thus, Section 8-5

Example 1: An educator estimates that the dropout rate for seniors at high schools in New Jersey is 15%. Last year, 38 seniors from a random sample of 200 New Jersey seniors withdrew. At α = 0.05, is there enough evidence to reject the educator’s claim? Section 8-5

Example 2: A telephone company representative estimates that 40% of its customers have call waiting service. To test this hypothesis, she selected a sample of 100 customers and found that 37% have call waiting. At α = 0.01, is there enough evidence to reject the claim? Section 8-5

Example 3: A statistician read that at least 77% of the population oppose replacing $1 bills with $1 coins. To see if the claim is valid, the statistician selected a sample of 80 people and found that 55 were opposed to replacing the $1 bills. At α = 0.01, test the claim that at least 77% of the population are opposed to the change. Section 8-5

Homework:  Pg 434: #’s Section 8-5