A random sample of 337 college students was asked

Number of faculty. the numbers of faculty at 32 randomly selected state-controlled colleges and universities with enrollment under 12,000 students are shown below. use these data to estimate the mean number of faculty at all state-controlled colleges and universities with enrollment under 12,000 with 92% confidence. assume image2.png.

211

384

396

211

224

337

395

121

356

621

367

408

515

280

289

180

431

176

318

836

203

374

224

121

412

134

539

471

638

425

159

324

Q # 14

Number of jobs. a sociologist found that in a sample of 50 retired men, the average number of jobs they had during their lifetimes was 7.2. the population standard deviation is 2.1.

a. find the best point to estimate of the population men.

b.find the 95 % confidence interval of the mean number of jobs.

c.find the 99% confidence interval of the mean number of jobs.

d. which is smaller? explain why.

Q # 18

Day care tuition. a random sample of 50 four-year-olds attending day care centers provided a yearly tuition average of $3987 and the population standard deviation of $630. find the 90% confidence interval of the true mean. if a day care center were starting up and wanted to keep tuition low. what would be a reasonable amount to charge?

Exercise 7-2

Q # 8

State Gasoline Taxes. a random sample of state gasoline taxes ( in cents ) is shown here for 12 states. use the data to estimate the true population mean gasoline tax with 90% confidence. does your interval contain the national average of 44.7 cents?

38.4

40.9

67

32.5

51.5

43.4

38

43.4

50.7

35.4

39.3

41.4

Q # 10

Dance Company Students. the number of students who belong to dance company at each of several randomly selected small universities is shown below. estimate the true population mean size of a university dance company with 99% confidence.

21

25

32

22

28

30

29

30

47

26

35

26

35

26

28

28

32

27

40

Exercise 7-3

Q # 6

Belief in haunted places. a random sample of 205 college students were asked if they believed that places could be haunted, and 65 responded yes. estimate the true proportion of college students who believed in the possibility of haunted places with 99% confidence. according to time magazine,37% of americans believe that places can be haunted.

Q # 14

Fighting U.S hunger. in a poll of 1000 likely voters, 560 say that the united states spends too little on fighting hunger at home. find a 95% confidence interval for the true proportion of voters who feel this way.

Exercise 8-2

Q # 4

Moviegoers. the average moviegoer sees 8.5 movies a year. a moviegoer is defined as a person who sees at least one movie in a theater in a 12 month period. a random sample of 40 moviegoers from a large university revealed that the average number of movies seen per person was 9.6. The population standard deviation is 3.2 movies. at the 0.05 level of significance, can it be concluded that this represents a difference from the national average?

Q # 8

Salaries of government employees. the mean salary of federal government employees on the general schedule is $59,593. the average salary of 30 state employees who do similar work is $58,800 with image4.png. at the 0.01 level of significance, can it be concluded that state employees earn on average less than federal employees?

Q # 12

Student expenditures. the average expenditure per student ( based on average daily attendance) for a certain school year was $10,337 with a population standard deviation of $1560. a survey for the next school year of 150 randomly selected students resulted in a sample mean of $10,798. do these results indicates that the average expenditure has changed? choose your own level of significance.

Exercise 8-3

Q # 6

Park acreage. a state executive claims that the average number of acres in western pennsylvania state parks is less that 2000 acres. a random sample of five parks is selected, and the number of acres is shown. at image6.png, is there enough evidence to support the claim?

959

1187

493

6249

541

Q # 14

Chocolate chip cookie calories. the average 1-ounce chocolate chip cookie contains 110 calories. a random sample of 15 different brands of 1-ounce chocolate chip cookies resulted in the following calorie amounts. at the image8.png, is there sufficient evidence that the average calorie content is greater than 110 calories?

100

125

150

160

185

125

155

145

160

100

150

140

135

120

110

Exercise 8-4

Q # 8

Female Physicians. the percentage of physicians who are women is 27.9%. in a survey of physicians employed by a larger university health system,45 of 120 randomly selected physicians were women. is there sufficient evidence at the 0.05 level of significance to conclude that the proportion of women physicians at the university health system exceeds 27.9%?