Please NOTE THAT i ONLY NEED THE ANSWER TO B BELOW which is "find the critical value". Thank you.

Before a trucking company switched to its currentcomputer-based billingsystem, the average payment time from customers was approximately 40 days. Suppose before purchasing the present billingsystem, it performed a test by examining a random sample of 29 invoices to see if the system would reduce the average billing time. The sample indicates that the average payment time is 38.7 days. Complete parts a and b.

a.

The company that created the billing system indicates that the system would reduce the average billing time to less than 40 days. Conduct a hypothesis test to determine if the newcomputer-based billing system would reduce the average billing time to less than 40 days. Assume the standard deviation is known to be 6 days. Use a significance level of 0.05.

Choose the correct hypotheses below.

A.

H0: 38.7

HA: >38.7

B.

H0: 38.7

HA: <38.7

C.

H0: 40

HA: >40

D.

H0: 40

HA: <40

Your answer is correct.

Find the test statistic z.

z=

negative 1.17

1.17 (Round to two decimal places asneeded.)

b. Find the critical value.

z=

(Round to three decimal places asneeded.)