Statistics Week 5
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A soccer ball manufacturer wants to estimate the mean circumference of soccer balls within 0.05 in. (a) Determine the minimum sample size required to construct a 90% confidence interval for the population mean. Assume the population standard deviation is 0.20 in. (b) Repeat part (a) using a population standard deviation of 0.40 in. Which standard deviation requires a larger sample size? Explain.
russellc, , Statistics, 0 
Find the minimum sample size n needed to estimate p for the given values of c, a, and E.
russellc, , Statistics, 0
c = 0.90. a = 9.9. and E = 2 Answer = 67

You are given the sample mean and the population standard deviation. Use this information to construct the 90% and 95% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals. If convenient, use technology to construct the confidence intervals. A random sample of 60 home theater systems has a mean price of $140. Assume the population standard deviation is $15.40 Construct a 90% confidence interval for the population mean. The 90% confidence interval is (nothing,nothing).
russellc, , Statistics, 0 

A nutritionist claims that the mean tuna consumption by a person is 3.9 pounds per year. A sample of 60 people shows that the mean tuna consumption by a person is 3.5 pounds per year. Assume the population standard deviation is 1.11 pounds. At alpha equals 0.1, can you reject the claim?
russellc, , Statistics, 0
see excel spreadsheet. This your answer

Determine whether the claim stated below represents the null hypothesis or the alternative hypothesis. If a hypothesis test is performed, how should you interpret a decision that (a) rejects the null hypothesis or (b) fails to reject the null hypothesis? A scientist claims that the mean incubation period for the eggs of a species of bird is less than 57 days.
russellc, , Statistics, 0
see excel spreadsheet. This your answer

A credit card company claims that the mean credit card debt for individuals is greater than $ 5000. You want to test this claim. You find that a random sample of 30 cardholders has a mean credit card balance of $ 5202 and a standard deviation of $ 600. At alpha equals 0.01, can you support the claim? Complete parts (a) through (e) below. Assume the population is normally distributed.
russellc, , Statistics, 0
see excel spreadsheet. This your answer