A Mail-Order Business Prides Itself in Its Ability to Fill $\alpha$

Multiple Choice

A mail-order business prides itself in its ability to fill customers' orders in less than six calendar days,on average.Periodically,the operations manager selects a random sample of customer orders and determines the number of days required to fill the orders.On one occasion when a sample of 39 orders was selected,the average number of days was 6.65 with a sample standard deviation of 1.5 days.What is the critical value for $\alpha$ = .10 to test the hypotheses.

A) -1.28
B) -1.96
C) -2.33
D) 1.28
E) 1.96