Hyper-one Store chain issues its own credit card. Lisa, the credit manager, wants to find out if the mean monthly unpaid balance is more than $400. The level of significance is set at 0.05. A random check of 172 unpaid balances revealed the sample mean to be $407 and the sample standard deviation to be $38. Should Lisa conclude that the population mean is greater than $400, or is it reasonable to assume that the difference of $7 is due to chance?

The null hypothesis is

The alternate hypothesis is

The calculated statistic is  (leave 4 decimal places only)

The tabulated critical value is retrieved from which table (write Z or T)

The tabulated critical value is  

Decision (write the letter a if you will reject Ho or write the letter b if you will not reject H0, your answer should be either a or b )

what can you conclude about the value of the mean monthly unpaid balance?