BER345 Homework #9 Covers Sections 9.2 and 9.3 1. The average temperatures for a 25-day period for Birmingham, Alabama, and Chicago, Illinois, are
BER345 Homework #9
Covers Sections 9.2 and 9.3
1. The average temperatures for a 25-day period for Birmingham, Alabama, and Chicago, Illinois, are shown below. Based on the samples, at α = 0.10, can it be concluded that it is significantly warmer in Birmingham? Solve using the traditional method.
Birmingham: 
= 73.85
S12 = 29.15
n1 = 25
Chicago: 
= 70.75
S22 = 34.83
n2 = 25
2. A real estate agent wishes to determine whether tax assessors and real estate appraisers agree on the vales of homes. A random sample of the two groups appraised 10 homes. The mean and standard deviations are shown below. Is there a significant difference in the values of the homes for each group? Let 
Test the hypothesis that the two appraisers differ in their appraisal values of the 10 homes. Solve using the traditional method.
Tax Assessors: = $87,344
S1 = $2252
n1 = 10
Real Estate Appraisers: = $84,856
S2 = $3175
n2 = 10
3. Construct a 95% Confidence Interval for the true mean difference in the appraisal values.
In an effort to improve the vocabulary of 10 students, a teacher provides a weekly 1-hour tutoring session for them. A pretest is given before the sessions, and a posttest is given afterward. The results are shown in the table. At α = 0.01, can the teacher conclude that the tutoring sessions helped to improve the students’ vocabularies? Solve using the traditional method.
| Student | 10 | |||||||||
| Pretest | 83 | 76 | 92 | 64 | 82 | 68 | 70 | 71 | 72 | 63 |
| Posttest | 88 | 82 | 100 | 72 | 81 | 75 | 79 | 68 | 81 | 70 |
D̅= -5.5
SD = 4.17
n = 10
4. In an effort to investigate how 10 college students retain information from a 19th century novel, a teacher shows them a movie about the novel after they finished reading the book. A pre-test is given before the movie and a post-test is given after the movie. The results are shown in the table. At α = 0.01, can the teacher conclude that the movie helped to improve the students’ retention of information? Solve using the traditional method.
| Student | 10 | |||||||||
| Pre-test | 85 | 72 | 80 | 75 | 70 | 75 | 80 | 76 | 68 | 73 |
| Post-test | 90 | 85 | 81 | 72 | 70 | 83 | 84 | 80 | 71 | 83 |
= -4.5
SD = 4.79
n = 10
5. Construct a 95% confidence interval for the mean difference in the number of points that changed between the pre-test and the post-test after watching the movie. Interpret the confidence interval.
