Question 1

Two hundred students took a standard chemistry test. You sampled 20 students to estimate the average score and the standard deviation. How many degrees of freedom were there in the estimation of the standard deviation?

Group of answer choices

19

20

40

21

Question 2

_________________refers to whether or not an estimator tends to overestimate or underestimate a parameter. ______________refers to how much the estimate varies from sample to sample.

Group of answer choices

Bias; standard error

Sample variability; Bias

Standard deviation; Mean

Mean; standard deviation

Question 3

A company just purchased 1,000 flat screen TVs. From the product label, the weight of one TV should be 15.4 pound which is considered the process average. The manager of the company randomly selected 20 TVs and measured their weight. Then, he repeated this procedure again three times. The means and standard errors are listed as follows. Which sample estimate shows the least bias?

Group of answer choices

Sample four: mean=17.0, SE=2.0

Sample three: mean=16.5, SE=1.5

Sample one: mean=16.0, SE=1.0

Sample two: mean=15.0, SE=0.6

Question 4

Which of the following statements is correct regarding a 95% confidencecalculated forthe following sample data: 88 77 86 92 97 75 68 78.

Group of answer choices

In the long run, with the same sample size used in determining the interval, the true mean of the sample will not be in the interval 5% of the time.

A confidence interval may be determined using the Z table.

For any sample size taken from the process, the true mean of thetrue mean of the populationwill be in the interval 95% of the time.

In the long run, with the same sample size used in determining the interval, the true mean of the population will be in the interval 95% of the time.

Question 5

Twenty students took a chemistry test. We randomly selected 5 students and observed their grades to be 90, 56, 86, 84, 56. The sample mean is 74.4 and variance is 286.8 What's the standard error of the mean from our sample estimate?

Group of answer choices

16.94

7.58

128.26

58.34

Question 6

Use of the Z table when determining confidence intervals assumes

Group of answer choices

The population standard deviation is known.

The mean of the population is known.

The standard error of the mean is small

The sample size is large

Question 7

A heart study was conducted on 312 women and cholesterol levels were measured. The average cholesterol level was 199.4 with a standard deviation of 35.0.

What is the 85% confidence interval for the true average cholesterol level of the population from which the women were sampled?

Group of answer choices

[198.2,200.6]

[197.4,201.5]

[196.6, 202.3]

[199.2,199.6]

Question 8

Imagine a sample of 14 subjects with a mean score of 22 and standard error of the mean of 3. What's the lower limit for the 99% confidence interval of the mean?

Group of answer choices

15.12

13.07

16.69

12.96

Question 9

A compression test was performed on 12 concrete blocks. The strength of the blocks averaged 2560 psi with a standard deviation of 155. What is the 95% lower confidence bound for the strength of the blocks? (one sided)

Group of answer choices

2423

2483

2480

2461

Question 10

A researcher wanted to study the years of education of the adult population in a certain community. He randomly sampled nine adults and obtained the mean years of education was 12.1 and the standard deviation was 2.4. What's the upper 95% confidence bound for the level of education? (one sided)

Group of answer choices

13.59

12.80

10.61

13.94