#1) For the problems below, explain which distribution you would use to set up a confidence interval. Make sure you explain why you chose the distribution. Also explain which formula you would use to help with the confidence interval and why you chose that one. You do not have to actually do any confidence intervals.

Choose from these distributions:

Standard Normal Distribution (z) The t-Distribution The chi - square Distribution Choose from these formulas:

Problem A) In a random sample of 12 dental assistants, the mean annual earnings was $31,721 and the standard deviation was $5260. Assume the annual earnings are normally distributed. Explain which distribution and which formula(s) you would use to construct a confidence interval for the population standard deviation.

Problem B) The data set represents the scores of 12 randomly selected students on the SAT Physics Subject Test. Assume the population test scores are normally distributed. Explain which distribution and which formula(s) you would use to construct a confidence interval for the population mean.

670 740 630 620 730 650 720 620 640 500 670 760

Problem C) In a random sample of 120 people, 58 said they would leave a tip when ordering at a coffee shop. Explain which distribution and which formula(s) you would use to construct a confidence interval for the population proportion.

Problem D) In a random sample of 35 boxes of cereal, the mean volume was 24.03 ounces. The population standard deviation of the volume is known to be 0.005 ounces. Explain which distribution and which formula(s) you would use to construct a confidence interval for the population mean.

Problem E) In a random sample of 29 students, the mean cost of materials for one quarter was $172.81, and the standard deviation was $9.39. Explain which distribution and which formula(s) you would use to construct a confidence interval for the population mean.

#2) In a survey of 3110 U.S. adults, 1435 say they have stared paying bills online in the the last year. Construct a 95% confidence interval for the population proportion. Interpret the results.

#3) The annual earnings of 14 randomly selected computer software engineers have a sample standard deviation of $3725. Assume the sample is from a normally distributed population. Construct an 80% level of confidence for the population standard deviation. Interpret the results.