1.A university surveyed recent graduates of the English Department for their starting salaries. Four hundred graduates returned the survey. The average salary was $25,000, with a standard deviation of $2,500. What is the best point estimate of the population mean?

$25,000

$2,500

$400

$62.5

2.Mileage tests were conducted on a randomly selected sample of 100 newly developed automobile tires. The results showed that the mean tread life was 50,000 miles, with a standard deviation of 3,500 miles. What is the best estimate of the mean tread life in miles for the entire population of these tires?

50,000

3,500

500

35

3.A survey of an urban university (population of 25,450) showed that 750 of 1,100 students sampled attended a home football game during the season. Using the 99% level of confidence, what is the confidence interval for the proportion of students attending a football game?

[0.7671, 0.8143]

[0.6550, 0.7050]

[0.6464, 0.7172]

[0.6805, 0.6815]

4.A random sample of 20 items is selected from a population. When computing a confidence interval for the population mean, what number of degrees of freedom should be used to determine the appropriatet-value?

20

19

21

25

5.The mean number of travel days per year for salespeople employed by three hardware distributors needs to be estimated with a 0.90 degree of confidence. For a small pilot study, the mean was 150 days and the standard deviation was 14 days. If the population mean is estimated within two days, how many salespeople should be sampled?

133

452

511

2,100

6.What kind of distribution is thetdistribution?

Continuous

Discrete

Subjective

Azdistribution

7.Which statement(s) is/are correct about thetdistribution?

The mean is zero

Its shape is symmetric

Its dispersion is based on degrees of freedom.

All apply

8.A population has a known standard deviation of 25. A simple random sample of 49 items is taken from the selected population. The sample mean (x-bar) is 300. What is themargin of errorat the 95% confidence level?

8

293

7

308

9.Which of the following is a point estimate for the population mean ()?

x/n

-x

s

10.A group of statistics students decided to conduct a survey at their university to find the average (mean) amount of time students spent studying per week. They sampled 240 students and found a mean of 22.3 hours per week. Assuming a population standard deviation of six hours, what is the 99% level of confidence?

[21.80, 22.80]

[16.3, 28.3]

[21.30, 23.30]

[20.22, 22.0]

11.Knowing the population standard deviation, a 95% confidence interval infers that the population mean ___________.

is between 0 and 100%

is within 1.96 standard deviations of the sample mean

is within 1.96 standard errors of the sample mean

is too large

12.A sample of 100 students is selected from a known population of 1000 students to construct a 95% confidence interval for the average SAT score. What correction factor should be used to compute the standard error?

0.949

0.901

1.96

Cannot be determined

13.University officials say that at least 70% of the voting student population supports a fee increase. If the 95% confidence interval estimating the proportion of students supporting the fee increase is [0.75, 0.85], what conclusion can be drawn?

Seventy percent is not in the interval, so another sample is needed.

Seventy percent is not in the interval, so assume it will not be supported.

The interval estimate is above 70%, so infer that it will be supported.

Since this was not based on the population, no conclusion can be drawn.