BUSINESS STATISTIC

Business statistic



Business statistic

The answers are indicated in bold:

1. An interval estimate is used to estimate

the shape of the population's distribution

the sampling distribution

a sample statistic

population parameter

2. An estimate of a population parameter that provides an interval believed to contain the value of the parameter is known as the

confidence level

interval estimate

parameter value

population estimate

3. As the sample size increases, the margin of error

increases

decreases

stays the same

None of the other answers are correct.

4. The ability of an interval estimate to contain the value of the population parameter is described by the

confidence level

degrees of freedom

Precise value of the population mean?

None of the other answers are correct.

5. The z value for a 97.8% confidence interval estimation is

2.02

1.96

2.00

2.29

6. It is known that the variance of a population equals 1,936. A random sample of 121 has been taken from the population. There is a .95 probability that the sample mean will provide a margin of error of

7.84 or less

31.36 or less

344.96 or less

1,936 or less

Exhibit 8-1

In order to estimate the average time spent on the computer terminals per student at a local university, data were collected from a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.2 hours.

7. Refer to Exhibit 8-1. The standard error of the mean is

7.5

0.014

0.160

0.133

8. Refer to Exhibit 8-1. With a 0.95 probability, the margin of error is approximately

0.26

1.96

0.21

1.64

9. Refer to Exhibit 8-1. If the sample mean is 9 hours, then the 95% confidence interval is approximately

7.04 to 110.96 hours

7.36 to 10.64 hours

.80 to 10.20 hours

8.74 to 9.26 hours

Exhibit 8-3

A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed, with a standard deviation of 13.5 mph.

10. Refer to Exhibit 8-3. If we are interested in determining an interval estimate for? at 86.9% confidence, the z value to use is

1.96

1.31

1.51

2.00

11. Refer to Exhibit 8-3. The value to use for the standard error of the mean is

13.5

9

2.26

1.5

12. Refer to Exhibit 8-3. The 86.9% confidence interval for? is

46.500 to 73.500

57.735 to 62.265

59.131 to 60.869

50 to 70

13. Refer to Exhibit 8-3. If the sample size was 25 (other factors remain unchanged), the interval would

not change

become narrower

become wider

become zero

14. Whenever the population standard deviation is unknown, which distribution is used in developing an interval estimate for a population mean?

standard distribution

z distribution

binomial distribution

t distribution

15. From a population that is normally distributed with an unknown standard deviation, a sample of 25 elements is selected. For the interval estimation of (?, the proper distribution to use is the

standard normal distribution

z distribution

t distribution with 26 degrees of freedom

t distribution with 24 degrees of freedom ...