Green Line, a major discount stock brokerage in Canada, claims that customers calling in to make trades on the stock market are left on hold for an average of about 22 seconds. Suppose that an account executive was concerned about the satisfaction level of the clients and selected a random sample of 100 traders who phoned. The length of time that a client was left on hold was recorded. Assume that the sample mean was 23.5 seconds with a standard deviation of 8 seconds.

Is there sufficient evidence to indicate that customers are left on hold for an average length of time greater than 22 seconds? Use a 5% level of significance.
Estimate the p-value for this test.
Based on the p-value will you reject Ho at the 5% significance level?
Would you reject Ho if the significance level were changed to 2.5%?