111. Confidence Intervals Large Samples

1. If we are constructing a 98 percent confidence interval for the population mean, the confidence level will be

(a) 2 percent.

(b) 2.29.

(c) 98 percent.

(d) 2.39.

2. The Z Value corresponding to a 97 percent confidence interval is

(a) 1.88.

(b) 2.17

(c) 1.96.

(d) 3 percent.

3. As the sample size increases, the confidence interval for the population mean will

(a) decrease.

(b) increase.

(c) stay the same.

(d) decrease and then increase.

4. If we change the confidence level from 98 % to 95 % when constructing a confidence interval for the population mean, we can expect the size of the interval to

(a) increase.

(b) decrease.

(c) stay the same.

(d) do none of the above.

5. Generally, lower confidence levels will yield

(a) smaller standard deviations for the sampling distribution

(b) larger margins of error.

(c) broader confidence intervals.

(d) narrower confidence intervals.

6. If the 98 percent confidence limits for the population mean μ Are 73 and 80, which of the following could be the 95 percent confidence limits?

(a) 73 and 81

(b) 72 and 79

(c) 72 and 81

(d) 74 and 79

7. A 90 percent confidence interval for a population mean indicates that

(a) we are 90 percent confident that the interval will contain all possible sample means with the same sample size taken from the given population.

(b) we are 90 percent confident that the population mean will be the same as the sample mean used in constructing the interval.

(c) we are 90 percent confident that the population mean will fall within the interval.

(d) none of the above is true.

8. Interval estimates of a parameter provide information on

(a) how close an estimate of the parameter is to the parameter.

(b) what proportion of the estimates of the parameter are contained in the interval.

(c) exactly what values the parameter can assume.

(d) the Z Score.

9. Which of the following confidence intervals will be the widest?

(a) 90 percent

(b) 95 percent

(c) 80 percent

(d) 98 percent

10. The best point estimate for the population variance is

(a) a statistic.

(b) the sample standard deviation.

(c) the sample mean.

(d) the sample variance.

11. When determining the sample size in constructing confidence intervals for the population mean μ, For a fixed maximum error of estimate and level of confidence, the sample size will

(a) increase when the population standard deviation is decreased.

(b) increase when the population standard deviation is increased.

(c) decrease when the population standard deviation is increased.

(d) decrease and then increase when the population standard deviation is increased.

12. When computing the sample size to help construct confidence intervals for the population proportion, for a fixed margin of error of estimate and level of confidence, the sample size will be maximum when

(a) P = 0.25.

(b) (1 – P) = 0.25.

(c) P(1 – P) = 0.5.

(d) P = 0.5.

13. What value of the population proportion P will maximize P(1 – P)?

(a) 0.50

(b) 0.25

(c) 0.75

(d) 0.05

14. Suppose that a sample of size 100 is selected from a population with unknown variance. If this information is used in constructing a confidence interval for the population mean, which of the following statements is true?

(a) The sample must have a normal distribution.

(b) The population is assumed to have a normal distribution.

(c) Only 95 percent confidence intervals may be computed.

(d) The sample standard deviation cannot be used to estimate the population standard deviation because the sample size is large.

< Предыдущая		Следующая >