2. For a hypothesis comparing two population means, what is the critical value for a one-tailed hypothesis test, using a 5% level of significance level, with both sample sizes equal to 13? The standard deviations for the samples are 5 and 7. Assume the population standard deviations are unequal.

2.064

1.711

2.074

1.717

3. A drug company is considering marketing a new local anesthetic. The effective time of the anesthetic the drug company is currently producing has a normal distribution with a mean of 7.4 minutes with a standard deviation of 1.2 minutes. The chemistry of the new anesthetic is such that the effective time should be normally distributed with the same standard deviation, but the mean effective time may be lower. If it is lower, the drug company will market the new anesthetic; otherwise, it will continue to produce the older drug. A sample of size 36 results in a sample mean of 7.1. A hypothesis test will be done to help make the decision.

Referring to Table 9-4, the appropriate hypotheses are:

H₀: 7.4 versusH₁:> 7.4.

H₀:> 7.4 versusH₁: 7.4.

H₀:= 7.4 versusH₁: 7.4.

H₀: 7.4 versusH₁:< 7.4.

5. A national manufacturer of ball bearings is experimenting with two different processes for producing precision ball bearings. It is important that the diameters be as close as possible to an industry standard. The output from each process is sampled and the average error from the industry standard is calculated. The results are presented below.

The researcher is interested in determining whether there is evidence that the two processes yield different average errors. Assume that the population standard deviations are equal.

What is the computed value oft?

+2.797

- 2.797

-13.70

+13.70

8. Accounting procedures allow a business to evaluate their inventory at LIFO (Last In First Out) or FIFO (First In First Out). A manufacturer evaluated its finished goods inventory (in $ thousands) for five products both ways. Based on the following results, is LIFO more effective in keeping the value of his inventory lower?

Product FIFO LIFO

1. 225221

2. 119100

3. 100113

4. 212200

5. 248245

What is the alternate hypothesis?

Uf = uL

Uf =/ uL.

Uf < uL.

Uf > uL.

10. Suppose we are testing the difference between two proportions at the 0.05 level of significance. If the computedzis1.07, what is our decision?

Reject the null hypothesis

Do not reject the null hypothesis

Take a larger sample

Reserve judgment