Statistics

The t distribution is a continuous
distribution (Points : 6)

True

False

2. A confidence interval for a
population mean (Points : 6)

estimates the population range

estimates a likely interval for a
population mean

estimates a likelihood or
probability

estimates the population standard
deviation

3. A 95% confidence interval
infers that the population mean (Points : 6)

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

4. What is the interval within
which a population parameter is expected to lie? (Points : 6)

Sample

Expected Value

Standard Deviation

Confidence Interval

5. Please choose the appropriate
answer for the cut-off/critical value ranges to go in the blank for each
question (5-8):

One-Tailed

Two-Tailed

95% (or .05) significance level
Question 5.

99% (or .01) significance level

(Points : 6)

-2.58 and 2.58

-1.65 or 1.65

-1.96 and 1.96

-2.33 or 2.33

6. Please choose the appropriate
answer for the cut-off/critical value ranges to go in the blank for each
question (5-8):

One-Tailed

Two-Tailed

95% (or .05) significance level

Question 6.

99% (or .01) significance level

(Points : 6)

-2.58 and 2.58

-1.65 or 1.65

-1.96 and 1.96

-2.33 or 2.33

7. Please choose the appropriate
answer for the cut-off/critical value ranges to go in the blank for each
question (5-8):

One-Tailed

Two-Tailed

95% (or .05) significance level

99% (or .01) significance level

Question 7.

(Points : 6)

-2.58 and 2.58

-1.65 or 1.65

-1.96 and 1.96

-2.33 or 2.33

8. Please choose the appropriate
answer for the cut-off/critical value ranges to go in the blank for each
question (5-8):

One-Tailed

Two-Tailed

95% (or .05) significance level

99% (or .01) significance level

Question 8.

(Points : 6)

-2.58 and 2.58

-1.65 or 1.65

-1.96 and 1.96

-2.33 or 2.33

9. To determine the size of a
sample, the standard deviation of the population must be estimated by either
taking a pilot survey or by approximating it based on knowledge of the
population. (Points : 6)

True

False

10. The t distribution is based on
the assumption that the population of interest is normal or nearly normal.
(Points : 6)

True

False

11. Recently, 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?

(Points : 6)

$25,000

$2,500

$400

$62.50

12. Recently, 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 95% confidence
interval for the mean salary of all graduates from the English Department?

(Points : 6)

[$22,500, $27,500]

[$24,755, $25,245]

[$24,988, $25,012]

[$24,600, $25,600]

13. Recently, 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 do the confidence interval
results mean?

(Points : 6)

The population mean is in the
interval

The population mean is not in the
interval

The likelihood that any confidence
interval based on a sample of 400 graduates will contain the population mean is
0.95

There is a 5% chance that the
computed interval does not contain the population mean.

14. The proportion of junior
executives leaving large manufacturing companies within three years is to be
estimated within 3 percent. The 0.95 degree of confidence is to be used. A
study conducted several years ago revealed that the percent of junior executives
leaving within three years was 21. To update this study, the files of how many
junior executives should be studied?

(Points : 6)

594

612

709

897

15.

7. There are 2,000 eligible voters
in a precinct. 500 of the voters are selected at random and asked to indicate
whether they planned to vote for the Democratic incumbent or the Republican
challenger. Of the 500 surveyed, 350 said they were going to vote for the
Democratic incumbent. Using the 0.99 confidence coefficient, what are the
confidence limits for the proportion that plan to vote for the Democratic
incumbent?

(Points : 6)

0.647 and 0.753

0.612 and 0.712

0.397 and 0.797

0.826 and 0.926

16. In opening a new Curves, the
company advertises that, while on the Curves diet and workout routine, new members
lose an average of 10 pounds in the first two weeks with a population standard
deviation of 2.8 pounds. A random sample of 50 women who joined the program
revealed a mean loss of 9 pounds. At a .05 level of significance, use the steps
in hypothesis testing to see if we can conclude that those joining Curves on
average will lose less than 10 pounds.

Is this a one-tailed or two-tailed
test?

(Points : 5)

One Tailed

Two Tailed

17. In opening a new Curves, the
company advertises that, while on the Curves diet and workout routine, new
members lose an average of 10 pounds in the first two weeks with a population
standard deviation of 2.8 pounds. A random sample of 50 women who joined the
program revealed a mean loss of 9 pounds. At a .05 level of significance, use
the steps in hypothesis testing to see if we can conclude that those joining
Curves on average will lose less than 10 pounds.

What is the cut-off (critical)
value?

(Points : 5)

+/- 1.65

+/- 1.96

+/- 2.33

+/- 2.58