In a random sample of five people, the mean driving distance to work was 20.2 miles and the standard deviation was 5.9 miles. Assuming the population is normally distributed and using the t-distribution, a 99% confidence interval for the population mean u is (8.1, 32.3) (and the margin of error is 12.1). Through research, it has been found that the population standard deviation of driving distances to work is 4.5. Using the standard normal distribution with the appropriate calculations for a standard deviation that is known, find the margin of error and construct a 99% confidence interval for the population mean H. Interpret and compare the results. Identify the margin of error.

A study found that a 95% confidence interval for the mean μ of a particular population was computed from a random sample of 1200 people and found it to be 10 ± 4. Therefore, we may conclude:

Q. No.4 The U.S. Dairy Industry wants to estimate the mean yearly milk consumption. A sample of 16 people reveals the mean yearly consumption to be 60 gallons with a standard deviation of 20 gallons. d. Develop the 90 percent confidence interval for the population mean. e. Would it be reasonable to conclude that the population mean is 63 gallons?

In a random sample of seven cell​ phones, the mean full retail price was ​$402.50 and the standard deviation was ​$228.00. Assume the population is normally distributed and use the​ t-distribution to find the margin of error and construct a 95​% confidence interval for the population mean μ. Interpret the results.

In a random sample of eight cell​ phones, the mean full retail price was ​$431.50 and the standard deviation was ​$226.00. Assume the population is normally distributed and use the​ t-distribution to find the margin of error and construct a 90​% confidence interval for the population mean μ. Interpret the results.

A sample of size n = 36 is drawn from a population whose standard deviation is σ = 15.6. The sample mean is x = 94.5. Construct a 95% confidence interval.

In a random sample of seven cell​ phones, the mean full retail price was ​$474.50 and the standard deviation was ​$189.00. Assume the population is normally distributed and use the​ t-distribution to find the margin of error and construct a 99​% confidence interval for the population mean μ. Interpret the results.

A sample of size 25 was taken from a very large population. Sample statistics, x¯ and s, were used to find that the 95% confidence interval was (138.616, 163.384). x¯= s=

A random sample of 100 households was selected as part of a study on electricity usage, and the number of kilowatt-hours (kWh) was recorded for each household .The average usage was found to be 10.5 kWh. In a very large study in the previous year it was found that the standard deviation of the usage was 3.2 kWh. Assuming the standard deviation is unchanged and that the usage is normally distributed, calculate a 90% confidence interval for the mean usage (round to two decimals) a. (9.68 , 11.30) O b. (9.87 , 11.10) O c. (7.05 , 7.95) O d. None of these e. (9.97 , 11.00)

In a random sample of twelvetwelve ​people, the mean driving distance to work was 24.624.6 miles and the standard deviation was 4.54.5 miles. Assume the population is normally distributed and use the​ t-distribution to find the margin of error and construct a 9999​% confidence interval for the population mean muμ. Interpret the results.