Statistics Homework 5 problems

5 problems for statistics. must show all work. 

In-Class Assignment # 4 and # 5 11.20.13

Answer the following questions showing ALL of your work.

Number your steps and write legibly.

Complete and bring to class on 11.26.13

1. A congressional committee wishes to estimate the average annual subsidy received by tenant farmers in a
southern state. A random sample of 495 farms is taken, the sample mean is found to be $7,850 with a sample

standard deviation of $750. Compute the 99% confidence interval estimate of the annual subsidy?

2. Business statistics students claim that they spend at least 3 hours studying for and working through statistics
practice problems per week. A random sample of 44 college students enrolled in a business statistics course was

asked how many hours he or she spent practicing working statistics problems. The sample average was found to

be 2.4 hours per week with a standard deviation of 1.25 hours. Using the p-value method and α = .01, determine

if the students are studying the amount of time that was claimed.

3. You are the manager of a restaurant that delivers pizza to college dormitory rooms. You have just changed your
delivery process to a method that you think will reduce the mean time, from the order to the completion of the

delivery, down from the current 25 minute delivery time. A sample of 36 orders using the new delivery process

yields a sample mean of 22.4 minutes and a standard deviation of 6 minutes. Can you conclude that the new

delivery process has reduced the population mean delivery time? Use the p-value method and a significance level

of 2.5% to answer this question.

4. A survey is planned to determine the mean annual family medical expenses of employees of a large company.
The management of the company wishes to be 90% confident that the sample mean is correct to within $50 of the

population mean annual family medical expenses. A previous study indicates that the standard deviation is

approximately $400. How large of a sample size is needed?

5. Two hundred people are randomly chosen at a shopping mall to taste-test a new brand of fruit drink. They are
asked to rate the drink on a scale from 1 to 5, with 5 being very good and 1 being very bad. The results of the

survey reveal that the sample average rating is 3.63 with a standard deviation of 1.22. Compute the 90%

confidence interval estimate of the mean drink rating?