Q1. The police chief in Montgomery wants to know if the city's population feels that the police are doing a good job. In comparing this information for areas of the city, the police can learn if they have a community-relations problem in certain parts of the city. A survey reveals the data in the chart below.
ATTITUDE
|
Area of Montgomery
|
Good Job
|
Poor Job
|
|
West
|
35
|
48
|
|
Central
|
40
|
35
|
|
East
|
60
|
30
|
Using a = .05, test the hypothesis that there is a relationship between perceptions of police performance and area of the city for Montgomery. What might you tell the police chief?
Q2. A researcher is interested in differences in the use of sick days by younger and older adults working for a state agency. A random sample of 10 younger (under 30) and 10 older (over 50) workers yielded the following data in sick days used within the past 12 months. Use these data to test the null hypothesis of no difference in the use of sick days between younger and older adults. Use α = 0.05. What do your results indicate?
Younger Adults Older Adults
1 2
10 7
2 13
3 5
13 10
6 12
7 25
4 14
0 5
4 8
Question 3: A statistics instructor is interested in the correlation (Pearson r) between how many hours a student sleeps the night before the final examination and the students score on the final examination. Use the following information to answer the questions below.
|
Student
|
Sleep (hrs)
|
Final
|
|
Barbara
|
8
|
96
|
|
Michael
|
6.3
|
75
|
|
Tina
|
10.5
|
88
|
|
Sharene
|
6.8
|
65
|
|
Destiny
|
8.5
|
82
|
|
Courtney
|
7.5
|
70
|
|
William
|
9
|
100
|
|
Kobe
|
7.5
|
84
|
|
Missy
|
6.5
|
73
|
|
Jose
|
8.2
|
96
|
|
Jeffrey
|
8.7
|
87
|
(a) Compute a Pearson's correlation coefficient for these data.
(b) Determine whether the correlation is significant.
(d) Calculate the regression slope and Y-intercept.
(e) Use the regression equation to predict the final examination grade for a student who sleeps 7.0 hours.
Question 4: If an unbiased coin is flipped 3 times, what is the probability of getting exactly two heads?
Question 5: What is the probability of selecting two aces (without replacement) from a well-shuffled deck of cards?
Question 6: Assuming the population of all statistics students that have taken this class had mean total points at the end of the class of 300 with a standard deviation of 30.
a. What is the percentile rank for someone who got 350 points?
b. What percentage of students had between 275 and 375 points?
Question 7: The following data are the SAT scores for 12 randomly selected high school seniors.
1224 1223 987 692 947 723
837 721 747 540 623 1445
a) What is the standard error of the mean for these data?
b) What is the 90% confidence interval for the population mean (µ)?