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# t critical, confidence interval

2) Use Table 4 of the appendix to find tc for a 0.99 confidence level when the sample size is 4.

4) Use Table 4 of the Appendix to find tc for 0.95 confidence level when the sample size is 12.

6) Wildlife: Wolf Pups. The number of pups in the wolf dens of the southwestern United States is recorded below for 16 wolf dens.
5, 8, 7, 5, 3, 4, 3, 9
5 8 5 6 5 6 4 7

a) use a calculator with mean and standard deviation keys to verify that the sample mean is x with line over top =5.63 pups with sample standard deviation s = 1.78 pups.
B) Compute an 85% confidence interval for the population mean number of wolf pups per den in the southwestern United States.

10) Hospital: Charity Care. What percentage of hospitals provides at least some charity care? The following problem is based on information taken from State Health Care Data: Utilization, Spending, and Characteristics. Based on a random sample of hospital reports from eastern states, the following information was obtained, (units in percentage of hospitals providing at least some charity care):
57.1 56.2 53.0 66.1 59.0 64.7 70.1 64.7 53.5 78.2
Use a calculator with mean and sample standard deviation keys to verify that x (with line over x) = 62.3% and s = 8.0%. Find a 90% confidence interval for the population average µ of the percentage of hospitals providing at least some charity care.