Suppose you do not know the population mean fee charged to H&R Block customers last year. Instead, suppose you take a sample of size n=40 and find a sample mean of 175. Assume that the distribution for fees is normally distributed with a population standard deviation of $50.
a. Calculate the standard error of x bar?
b. 95% confidence interval for the population mean of fees at H&R Block.
i.Calculate the margin of error (MOE) of x bar using a 5% significance level.
ii.Calculate the 95% confidence interval.
iii.What is the interpretation of the confidence interval.
c. 90% confidence interval for the population mean of fees H&R Block.
i.Calculate the margin of error (MOE) of x bar using a 10% significance level.
ii.Calculate the 90% confidence interval.
iii.Suppose an analyst belief that the population mean fee is equal to $185. Using a 90% confidence level. can we conclude the analyst is right?