CH 8.1) Health insurers are beginning to offer telemedicine services online that replace the common office visit. Wellpoint provides a video service that allows subscribers to connect with a physician online and receive prescribed treatments. Wellpoint claims that users of its LiveHealth Online service saved a significant amount of money on a typical visit. The data shown below ($), for a sample of 20 online doctor visits, are consistent with the savings per visit reported by Wellpoint.
92 | 35 | 40 |
105 | 83 | 56 |
55 | 49 | 39 |
75 | 50 | 94 |
93 | 74 | 75 |
79 | 94 | 98 |
53 | 81 |
Assuming the population is roughly symmetric, construct a 95% confidence interval for the mean savings for a televisit to the doctor as opposed to an office visit (to 2 decimals).
95% confidence interval: $ ? to $ ? per visit
2. The Centers for Disease Control reported the percentage of people 18 years of age and older who smoke (CDC website, December 14, 2014). Suppose that a study designed to collect new data on smokers and nonsmokers uses a preliminary estimate of the proportion who smoke of .31.
a. How large a sample should be taken to estimate the proportion
of smokers in the population with a margin of error of .02 (to the
nearest whole number)? Use 95% confidence.
b. Assume that the study uses your sample size recommendation in
part (a) and finds 520 smokers. What is the point estimate of the
proportion of smokers in the population (to 4 decimals)?
c. What is the 95% confidence interval for the proportion of smokers in the population (to 4 decimals)?
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