Create an organizational behavior modification (OBM) plan to define behaviors that are required for successful job performance as a retail sales associate.
January 9, 2018
Charles Trout argues that “No American city entered 1930 a tabula rasa,” “rather, cities carried into the Great Depression their own particular economic practices, social structures, and political outlooks.”  What does he mean by that and how does this apply to Boston?
January 9, 2018

QNT 561 confidence interval Calculate confidence interval, Sample Size Estimation for Proportion

QNT 561 confidence interval

Calculate confidence interval, Sample Size Estimation for Proportion

1) In a random sample of 810 women employees, it is found that 81 would prefer working for a female boss. What is the width of the 95% confidence interval for the proportion of women who prefer a female boss? Please show your calculations

2)Suppose the President wants an estimate of the proportion of the population who oppose a policy toward gun control. The President wants the estimate to be within .04 of the true proportion. Assume a 95 percent level of confidence. The President’s political advisors estimated the proportion supporting the current policy to be 0.60. How large a sample is required?

3) Explain whether the width of a confidence interval would increase, decrease, or remain the same as a result of each of the following changes:

a) The sample size is doubled, from 400 to 800

b) The population size is doubled, from 25 million to 50 million

c) The level of confidence is lowered from 95% to 90%

4) A financial institution wishes to estimate the mean balances owed by its credit card customers. The population standard deviation is estimated to be $300. If a 99 percent confidence interval is used and an interval of ±$75 is desired, how many cardholders should be sampled?

5) A tire manufacturer wishes to investigate the tread life of its tires. A sample of 10 tires driven 50,000 miles revealed a sample mean of 0.32 inch of tread remaining with a standard deviation of 0.09 inch. Construct a 95 percent confidence interval for the population mean. Would it be reasonable for the manufacturer to conclude that after 50,000 miles the population mean amount of tread remaining is 0.30 inches? [compute the confidence of interval using t-distribution since σ is unknown]

 

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