# 1. A machine that produces a major part for an airplane engine is monitored closely

Question

1. A machine that produces a major part for an airplane engine is monitored closely. In the past, 10% of the parts produced would be defective. With a .95 probability, the sample size that needs to be taken if the desired margin of error is .04 or less is:

a. 110

b. 111

c. 216

d. 217

2If we change a 95% confidence interval estimate to a 99% confidence interval estimate, we can expect:

a. the size of the confidence interval to decrease.

b. the sample size to increase.

c. the size of the confidence interval to increase.

d. the size of the confidence interval to remain the same.

3The value added and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the:

a. margin of error.

b. parameter estimate.

c. confidence level.

d. interval estimate

4A simple random sample of 100 observations was taken from a large population. The sample mean and the standard deviation were determined to be 80 and 12 respectively. The standard error of the mean is:

a. 0.80

b. 0.12

c. 8.00

d. 1.20

5After computing a confidence interval, the user believes the results are meaningless because the width of the interval is too large. Which one of the following is the best recommendation?

a. Increase the level of confidence for the interval.

b. Reduce the population variance.

c. Decrease the sample size.

d. Increase the sample size.

6The level of significance

a. can be any positive value.

b. can be any value.

c. can be any value between -1.96 to 1.96.

d. is (1 – confidence level).

7In hypothesis testing,

a. the smaller the Type I error, the smaller the Type II error will be.

b. the sum of Type I and Ttype II errors must equal to 1.

c. the smaller the Type I error, the larger the Type II error will be.

d. Type II error will not be effected by Type I error.

8The probability of making a Type I error is denoted by

a. ?.

b. ?.

c. 1 – ?.

d. 1 – ?.

9The sample statistic s is the point estimator of:

a. ?

b.

c.

d. ?

10.An assumption made about the value of a population parameter is called a:

a. significance.

b. conclusion.

c. confidence.

d. hypothesis.

11.If a hypothesis is rejected at the 5% level of significance, it

a. will always be rejected at the 1% level.

b. will always be accepted at the 1% level.

c. may be rejected or not rejected at the 1% level.

d. will never be tested at the 1% level

12.A population characteristic, such as a population mean, is called:

a. a sample.

b. a statistic.

c. a parameter.

d. the mean deviation.

13.What type of error occurs if you fail to reject H0 when, in fact, it is not true?

a. Type I.

b. either Type I or Type II, depending on the level of significance.

c. Type II.

d. either Type I or Type II, depending on whether the test is one tail or two tail.

14.The average monthly rent for one-bedroom apartments in Chattanooga has been $700. Because of the downturn in the real estate market, it is believed that there has been a decrease in the average rental. The correct hypotheses to be tested are

a. H0:? < 700 Ha: ?? 700

b. H0: ?? 700 Ha: ? 700 Ha: ??700

d. H0: ? = 700 Ha: ?? 700

15.Foraone-tailedtest (uppertail),asamplesizeof26at90%confidence,t =

a. -1.316

b. -1.740

c.1.740

d.1.316

16.Whenthefollowinghypothesesarebeingtestedatalevelofsignificanceofa

H0:? ? 500

Ha: ? ?/2.

d. > ?.

17.The probability distribution of all possible values of the sample mean is:

a. the probability density function of .

b. the sampling distribution of .

c. one, since it considers all possible values of the sample mean.

d. the grand mean, since it considers all possible values of the sample mean.

18.The following random sample from a population whose values were normally distributed was collected.

The 95% confidence interval for ? is:

a. 7.75 to 12.25

b. 8.52 to 10.98

c. 8.00 to 10.00

d. 9.75 to 10.75

19.The p-value is a probability that measures the support (or lack of support) for the:

a. either the null or the alternative hypothesis.

b. null hypothesis.

c. sample statistic.

d. alternative hypothesis.

20.A random sample of 64 students at a university showed an average age of 25 years and a sample standard deviation of 2 years. The 98% confidence interval for the true average age of all students in the university is:

a. 24.4 to 25.6

b. 20.5 to 26.5

c. 20.0 to 30.0

d. 23.0 to 27.0

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