problem 1

After reading Chapter 10, select the best answer to the following problem:

If we are testing for the difference between the means of 2 independent populations presuming equal variances with samples of n1 = 20 and n2 = 20, the number of degrees of freedom is equal to:

39.
18.
19.
38.
Problem 2 (8.5 points)

After reading Chapter 11, select the most appropriate test for analyzing the data given in the following scenario:

An airline wants to select a computer software package for its reservation system. Four software packages (1, 2, 3, and 4) are commercially available. The airline will choose the package that bumps the fewest mean number of passengers as possible during a month. An experiment is set up in which each package is used to make reservations for 5 randomly selected weeks. (A total of 20 weeks was included in the experiment.) The number of passengers bumped each week is given below.

Package 1: 12, 14, 9, 11, 16
Package 2: 2, 4, 7, 3, 1
Package 3: 10, 9, 6, 10, 12
Package 4: 7, 6, 6, 15, 12

How should the data be analyzed? Select the best answer choosing from the following:

F test for differences in variances.
One-way ANOVA F test.
t test for the differences in means.
t test for the mean difference.