# The mortgage bankers association would like to

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Chapter 5 / Exercise 80
Trigonometry
Larson
Expert Verified
125) The Mortgage Bankers Association would like to estimate the proportion of delinquent mortgages in the state of Georgia. Determine the total sample size needed to construct a 90% confidence interval for the proportion of delinquent mortgages in Georgia with a margin of error equal to 4%. Answer: 126) The average grocery bill at the cash register for a random sample of 10 shoppers at a local store is \$53.80 with a sample standard deviation of \$18.40. Determine the margin of error for a 90% confidence interval for this sample. Answer: 127) The local Chamber of Commerce would like to estimate the average price of 93 octane gasoline for Chester County. There are currently 86 gas stations operating in the county. A random sample of 15 stations had an average price of \$4.20 per gallon and a standard deviation of \$0.24 per gallon. Determine the 95% confidence interval for the average price per gallon of 93 octane gasoline in Chester County. Answer: 28
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Chapter 5 / Exercise 80
Trigonometry
Larson
Expert Verified
128) The manager of Glendale Apartments would like to estimate the proportion of apartment units that watched the most recent Super Bowl on television. A random sample of 130 apartments found that 72 had watched the most recent Super Bowl. There are 460 units in Glendale Apartments. Determine the 90% confidence interval for the proportion of apartment units who watched the most recent Super Bowl. Answer: 129) Tire Kingdom installs automobile tires on a first - come first - served basis. A random sample of 50 customers experienced an average wait time of 93.7 minutes. Assume that the standard deviation of total wait time for all customers is 20.6 minutes. Determine the margin of error for a 95% confidence interval for this sample. Answer: 29
130) An HP inkjet printer ad advertises that the black ink cartridge will provide enough ink for an average of 270 pages. Assume that the standard deviation for this population is 16.5 pages. A random sample of 40 customers was surveyed about the number of pages they were able to print with their black ink cartridges. The sample average was 268.1 pages. Use a 95% confidence interval to test the validity of HP's claim.
131) The success of the Facebook business model depends on users clicking on ads when using the web site. A random sample of 260 Facebook users found that 111 of them click on the ads. Determine the 90% confidence interval for this sample.