B what is the probability that for each firm the

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b. What is the probability that for each firm the sample mean will be within 25 of the population mean μ (to 4 decimals)?
10. Refer to the Scheer Industries example in Section 8.2.
Use 6.82 days as a planning value for the population standard deviation. a. Assuming 95% confidence, what sample size would be required to obtain a margin of error of 1 days (round up to the next whole number)? b. Assuming 90% confidence, what sample size would be required to obtain a margin of error of 3 days (round up to the next whole number)? Top of Form 11. 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 ( Bloomberg Businessweek (March 4 – March 9, 2014). 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. 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 Top of Form 12. The president of Doerman Distributors, Inc., believes that 33% of the firm's orders come from first-time customers. A simple random sample of 100 orders will be used to estimate the proportion of first-time customers. a. Assume that the president is correct and
p = 0.33. What is the sampling distribution of p for this study?
What is the probability that the sample proportion will be between .26 and .40 (to 4 decimals)? c. What is the probability that the sample proportion will be between .31 and .35 (to 4 decimals)? Top of Form 13. The range for a set of data is estimated to be 68. a.
What is the planning value for the population standard deviation? At 95% confidence, how large a sample would provide a
margin of error of 4? At 95% confidence, how large a sample would provide a
margin of error of 2?
14. The following data are from a simple random sample. 4, 9, 13, 6, 13, 15 a.
What is the point estimate of the population mean?
What is the point estimate of the population standard deviation (to 1 decimal)?
15. The average cost per night of a hotel room in New York City is $266 (
, March 2009). Assume this estimate is based on a sample of 45 hotels and that the sample standard deviation is $60. a. With 95% confidence, what is the margin of error? Round your answer to the nearest dollar.
$ b. What is the 95% confidence interval estimate of the population mean? Round your answers to the nearest dollar. to c. Two years ago the average cost of a hotel room in New York City was $229. Discuss the change in cost over the two- year period. Bottom of Form Bottom of Form Bottom of Form Bottom of Form
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