Mba 510 Week 5

Chapter 10

For Exercises 1–4 answer the questions: (a) Is this a one- or two-tailed test? (b) What is the

decision rule? (c) What is the value of the test statistic? (d) What is your decision regarding H0?

(e) What is the p-value? Interpret it.

1. The following information is available.

H0: = 50

H1: =/ 50

The sample mean is 49, and the sample size is 36. The population standard deviation is 5.

Use the .05 significance level.

a. This problem is two-tailed because of the equal, not-equal signs.

b. The decision rule is to reject H0 and accept H1 when z does not fall between -1.96 and 1.96

c. -1.2, found by z = (49 - 50)/(5/ (sqrt of 36)) = -1.2

d. The decision is to reject H0.

e. p = 2(0.50 – 0.3849)

p = 0.2302

There is a 23.02% chance of z being this size when H0 is true.

3). A sample of 36 observations is selected from a normal population. The sample mean is 21,

and the sample standard deviation is 5. Conduct the following test of hypothesis using the

.05 significance level.

H0: _ 20

H1: _ 20

a. One tailed

b. Reject Ho and accept H1 when z>1.65

c. 1.2 found by z=(21-20)/(5/\ 36) = 1.2

d. Fail to reject Ho at the .05 significance level

e. P= .1151, found by .5000 - .3849. an 11.51% chance of finding a z value this large or larger

5).For Exercises 5–8: (a) State the null hypothesis and the alternate hypothesis. (b) State the

decision rule. (c) Compute the value of the test statistic. (d) What is your decision regarding H0? (e) What is the p-value? Interpret it.

The manufacturer of the X-15 steel-belted radial truck tire claims that the mean mileage the tire can be driven before the tread wears out is 60,000 miles. The standard deviation of the mileage is 5,000 miles. The Crosset Truck Company bought 48 tires and found that the mean mileage for their trucks is 59,500 miles. Is Crosset’s experience different from that claimed by the manufacturer at the .05 significance level?

Example:

a. Two-tailed.

b....