Question

A pizza place recently hired additional drivers and as a result now claims that its average delivery time for orders is under 45 minutes. A sample of 40 customer deliveries was​ examined, and the average delivery time was found to be 40.2 minutes.​ Historically, the standard deviation for delivery time is 10.5 minutes. Using alpha=0.01​, complete parts a and b below. a. Does this sample provide enough evidence to support the delivery time claim made by the pizza​ place? Determine the null and alternative hypotheses.

H_0:

H_1:

The z test statistic is_____

the critical z score(s) is(are)______

The test statistic (falls within/is less than/does not fall within/is greater than) the critical value, (reject/do not reject) the null hypothesis.

Answer 1

Solution :

This is the left tailed test .

The null and alternative hypothesis is ,

H₀ :   = 45

H_a : < 45

= 40.2

= 45

= 10.5

n = 40

Test statistic = z

= ( - ) / / n

= (40.2 - 45) / 10.5 / 40

= -2.89

Test statistic = -2.89

= 0.01

Z = Z_0.01 = -2.326

Critical value = -2.326

Test statistic < Critical value

Do not reject the null hypothesis .