Math 227 Fall2008 Homework 11

------

1-A firm wishes to compare four programs for training workers to perform a certain manual task. Twenty new employees are randomly assigned to the training programs, with 5 in each program. At the end of the training period, a test is conducted to see how quickly trainees can perform the task. The number of times the task is performed per minute is recorded for each trainee, with the following results:

Program 1 / Program 2 / Program 3 / Program 4
9 / 10 / 12 / 9
12 / 6 / 14 / 8
14 / 9 / 11 / 11
11 / 9 / 13 / 7
13 / 10 / 11 / 8

2-An economist wants to test whether mean housing prices are the same regardless of which of 3 air-pollution levels typically prevails. A random sample of house purchases in 3 areas yields the price data below.

HOUSING PRICES (THOUSANDS OF DOLLARS):

Low / Mod / High
120 / 61 / 40
68 / 59 / 55
40 / 110 / 73
95 / 75 / 45
83 / 80 / 64

3-Dr. Ghamsary is interested in the use of technology in the classroom. Suppose he does an experiment in which he teaches each of four sections of an introductory STAT class in a different way. One section of six students receives the standard lecture format (blackboard & discussion), a second section of six students receives the same lectures with the addition of overhead transparencies, the third section receives the lectures on the web, and the fourth section using power point slides with the same number of students. The dependent variable is performance on a standardized (final) exam. The data for the three groups follow. Do an analysis by hand (including a graph of the means) as well as using Minitab.

Lecture / Overheads / Web / Power points
70 / 72 / 90 / 81
71 / 75 / 80 / 78
65 / 69 / 76 / 85
88 / 80 / 95 / 92
60 / 51 / 80 / 85
72 / 75 / 82 / 91

4-Dr. Montgomery believes age is a significant predictor of GPA in college. He randomly selected 15 students from CSULB as follows. Test the claim that there is no difference in GPA for the 3 age categories.

Age

Less than 18 / 18-21 / >21
2.52 / 2.39 / 2.89
2.63 / 2.75 / 3.25
1.92 / 2.36 / 2.95
2.85 / 2.65 / 3.43
2.82 / 3.02
3.12

4