1. Suppose that an accounting firm does a study to determine the time needed to complete one person's tax forms. It randomly surveys 150 people. The sample mean is 22.2 hours. There is a known population standard deviation of 6.6 hours. The population distribution is assumed to be normal. NOTE: If you are using a Student's t-distribution, you may assume that the underlying population is normally distributed. (In general, you must first prove that assumption, though.)Which distribution should you use for this problem? (Round your answers to two decimal places.) X ~n ( , )

(b)Construct a 90% confidence interval for the population mean time to complete the tax forms. State the confidence interval. (Round your answers to two decimal places.)(____,____)

c) Calculate the error bound. (Round your answer to two decimal places.)

2. A camp director is interested in the mean number of letters each child sends during his or her camp session. The population standard deviation is known to be 2.4. A survey of 20 campers is taken. The mean from the sample is 7.3 with a sample standard deviation of 2.8. Find the following. (Enter exact numbers as integers, fractions, or decimals.)(i)x = (ii) = (iii)n =

b)Construct a 90% confidence interval for the population mean number of letters campers send home.(i) State the confidence interval. (Round your answers to two decimal places.) (___,___)

(iii) Calculate the error bound. (Round your answer to two decimal places.) 3. Suppose that a committee is studying whether or not there is waste of time in our judicial system. It is interested in the mean amount of time individuals waste at the courthouse waiting to be called for jury duty. The committee randomly surveyed 81 people who recently served as jurors. The sample mean wait time was seven hours with a sample standard deviation of four hours. (a)(i) Enter an exact number as an integer, fraction, or decimal. x = s_x = n = n 1 =

(b)Which distribution should you use for this problem? (Enter your answer in the form z or t_df where df is the degrees of freedom.)

(c) Construct a 95% confidence interval for the population mean time wasted.(i) State the confidence interval. (Round your answers to two decimal places.)

(ii)Sketch the graph. (Round your answers to two decimal places. Enter your /2 to three decimal places.)

(iii) Calculate the error bound. (Round your answer to two decimal places.)