Homework ch. 20-21

1. Homework ch. 20-21

2. 1. A toy manufacturer claims that at least 23% of the fourteen year old residents of a certain city own skateboards. A sample of 400 fourteen year olds shows that 70 own a skateboard. Test this claim at an α=0.05. H0 : p ≥ 0.23 claim H1: p < 0.23 Reject the null There is enough information to reject the that at least 23% of the fourteen year old residents of a certain city own skateboards.

3. 2. A past study found that at most 32% of people who have been in a plane crash have died. In a sample of 100 people who were in a plane crash 38 died. Use an α=0.05 to test the claim from the past study. • H0 : p ≤ 0.32 claim H1: p > 0.32 Not reject the null There is not enough information to reject the claim that at most 32% of people who have been in a crash have died.

4. A telephone company wants to advertise that more than 30% of all of its customers have at least two telephones. To support this advertisement, the company selects a sample of 200 customers and finds that 72 have more than two telephones. Use an α=0.01 to test this add. • H0 : p ≤ 0.30 H1: p > 0.30 claim Not reject the null There is not enough information to support the claim that more than 30% of all of its customers have at least two telephones

5. Researchers suspect that 18% of all high school students smoke at least one pack of cigarettes a day. At Wilson high school, with an enrollment of 300 students, a study found 50 students smoke at least one pack of cigarettes a day. At and α=0.10 test what the researchers suspect. • H0 : p = 0.18 claim H1: p ≠ 0.18 Not reject the null There is not enough information to reject the claim that 18% of all high school students smoke at least one pack of cigarettes a day