21.4 Gun ownership. In 2017, the Pew Research Center published the results of a survey on gun ownership. A random sample of 3930 American adults aged 18 years and older participated in this survey. Of these 3930 individuals, 1269 individuals reported that they owned at least one gun. Of these self-reported gun owners, 850 said the reason they owned a gun was for protection. Based on this information, we know the sample proportion, p^, of gun owners from this survey who own a gun for protection is

a. 0.042.

b. 0.216.

c. 0.323.

d. 0.670.

21.5 Barriers to travel. In their 2018 Travel Trends report, the American Association of Retired Persons reported the results of a survey of 374 adults between the ages of 20 and 36 years. Of the 374 individuals in this age group, 176 indicated that cost was the biggest barrier when it comes to traveling. Based on this information, the 95% confidence interval for the proportion of all adults in this age group who find cost to be the biggest barrier to travel would be

0.451 to 0.491.

0.445 to 0.497.

0.420 to 0.522.

0.397 to 0.545.

21.8 Pigs. A 90% confidence interval is calculated for a sample of weights of 135 randomly selected pigs, and the resulting confidence interval is from 75 to 90 pounds. Will the sample mean weight (from this sample of size 135) fall within the confidence interval?

A. No

b. Yes

c. Maybe

21.22 Harley motorcycles. In 2013, it was reported that 55% of the new motorcycles that were registered in the United States were Harley-Davidson motorcycles. You plan to interview an SRS of 600 new motorcycle owners.

a. What is the sampling distribution of the proportion of your sample who own Harleys?

b. How likely is your sample to contain 57% or more who own Harleys? How likely is it to contain at least 51% Harley owners? Use the 68-95-99.7 rule and your answer to part (a).

21.23 Do you jog? Suppose that 10% of all adult's jog. An opinion poll asks an SRS of 400 adults if they jog.

a. What is the sampling distribution of the proportion p^ in the sample who jog?

b. According to the 68-95-99.7 rule, what is the probability that the sample proportion who jog will be 7.3% or greater?