The operator of a nuclear power plant requires fuel rods to have a mean percentage of enrichment of 2.95. A fuel rod manufacturer takes a random sample of 12 specimens and reports their percentage of enrichment. The reported measurements were as follows. 2.94 2.90 3.00 2.75 2.90 | 2.75 2.82 3.00 2.95 3.05 2.95 2.81 What is the upper limit of a 99% two-sided confidence interval on the mean percentage of enrichment?

The EPA tests cars for city miles per gallon (mpg). For one model, a sample of 16 cars were tested for mpg, the results follow.   28 25.7 25.8 28 28.5 29.8 30.2 30.4 26.9 28.3 29.8 27.2 26.7 27.7 29.5 28 Find the 95% confidence interval for mean mpg.    Find the 99% confidence interval for mean mpg.

Tina catches a 14-pound bass.  She does not know the population mean or standard deviation.  So she takes a sample of five friends and they say the last bass they caught was 9, 12, 13, 10, and 10 pounds.  Find the t and calculate a 95% (α = .05) confidence interval.

Find the critical value tc for a 95% confidence level when the sample size is 18. Use Table 4 on page A10 (Appendix)   A. 1.740   B. 2.110   C. 2.101   D. 1.734

A tire manufacturer investigated the tread life of its tires. Samples of 10 tires driven 50,000 miles revealed a sample mean of 0.32 inch of tread remaining with a standard deviation of 0.09 inch. In the given problem, the 95% confidence interval for the population mean is? Select one: O a. 0.128-0.192 b. 0.256-0.384 O c. 0.512-0.768 O d. None of above

In a random sample of 5 mobile​ devices, the mean repair cost was ​$60.00 and the standard deviation was ​$12.00. Assume the population is normally distributed and use a​ t-distribution to find the margin of error and construct a 95​% confidence interval for the population mean. Interpret the results.

In a random sample of 17 people, the mean commute time to work was 30.2 minutes and the standard deviation was 7.1 minutes. Assume the population is normally distributed and use a t- distribution to construct a 95% confidence interval for the population mean y. What is the margin of error of y? Interpret the results.

Choose the appropriate statistical test. When computing, be sure to round each answer as indicated. A dentist wonders if depression affects ratings of tooth pain. In the general population, using a scale of 1-10 with higher values indicating more pain, the average pain rating for patients with toothaches is 6.8. A sample of 30 patients that show high levels of depression have an average pain rating of 7.1 (variance 0.8). What should the dentist determine? 1. Calculate the estimated standard error. (round to 3 decimals). [st.error] 2. What is thet-obtained? (round to 3 decimals). 3. What is the t-cv? (exact value) 4. What is your conclusion? Only type "Reject" or Retain"

In a sample of seven cars, each car was tested for nitrogen oxide emissions (in grams per mile). The results appear below. Assuming that nitrogen oxide emissions are normally distributed, 4. Car 1 2 3 4 5 6 7 Nitrogen oxide emission (g/mi) 0.13 0.18 0.15 0.09 0.12 0.18 0.08 a. Construct a 95% confidence interval for the mean amount of nitrogen oxide emissions for all cars. b. What effect would increasing the level of confidence have on the length of the interval?

create a 90% confidence interval for the following data:  x = 25 n = 100