Essentials of Statistics s1

Name:______Date:______

Labouré College

Essentials of Statistics

MAT 3410

Midterm Prep

Questions from Chapter 1

You are conducting a study of the levels of risk factors for diabetes in African Americans. Among the questions on your survey instrument are:

A. Do you have a family history of diabetes? 1) yes, 2) no, 3) don’t know.

B. What is your weight in pounds?______

1. Suppose you attend a health fair event aimed at African Americans. You sit at a booth and hand out your survey for attendees to fill out. What kind of sampling technique are you using (1 point)?

a. Simple random

b. Stratified

c. Systematic

d. Cluster

e. Multistage

f. Convenience

2. Is the variable for A qualitative or quantitative (1 point)?

a. Qualitative

b. Quantitative

3. Is the variable for B qualitative or quantitative (1 point)?

a. Qualitative

b. Quantitative

4. Is the variable for A nominal, ordinal, or ratio? (1 point)?

a. Nominal

b. Ordinal

c. Ratio

5. Is the variable for B nominal, ordinal, or ratio? (1 point)?

a. Nominal

b. Ordinal

c. Ratio

6. Is the average weight of everyone who filled out your survey a statistic or a parameter (1 point)?

a. Statistic

b. Parameter

7. You are surveying an African American population about their risk factors for diabetes. Is this an observational study or an experiment? (1 point)

a. Observational Study

b. Experiment

8. Suppose you feel that African Americans are overweight, and therefore, you only offer the survey to African Americans who come to your booth and appear to be overweight. What kind of research mistake is this? (1 point)

a. Undercoverage

b. Faulty recall

c. Hidden bias

d. Interviewer influence

Questions from Chapter 2

1. The following data represent the number of defective toys in a case of 500 toys coming off a production line. Every day for 35 consecutive days, a case was selected at random.
26 11 53 16 8 93 36
26 23 42 55 33 25 39
7 61 12 49 38 47 29
26 33 21 19 18 35 48
5 15 13 42 29 41 26

Select the correct stem-and-leaf display for the broken toys.

2. Select the correct histogram for the broken toys.

3. Identify the shape of the distribution for the broken toys.

a. Skewed left

b. Skewed right

c. Uniform

d. Normal/bell-shaped

Questions from Chapter 3

According to the American Hospital Directory (AHD.com), Missouri has 89 hospitals registered with Medicare. A researcher took a random sample of 10 hospitals and recorded the number of beds for each hospital. Here are the data points she used:

114 682 36 91 116 28 170 215 348 164

Answer the following questions with respect to this dataset of number of beds in a sample of 10 Missouri hospitals.

Round all calculations to 1-digit after the decimal.

1. What is the mean of the beds?

a. 196.4

b. 72.0

c. 37,703.6

d. 36.0

2. What is the median of the beds?

a. 116.2

b. 140.0

c. 194.2

d. There is no median

3. What is the mode of the beds? What is the mode of the beds?

a. 28

b. 114

c. 348

d. There is no mode

4. What is the range of the beds?

a. 682

b. 654

c. 697

d. 348

5. What is the Q1 of the beds?

a. 194.2

b. 164.8

c. 215.2

d. 91.0

6. What is the Q3 of the beds?

a. 215.0

b. 28.0

c. 682.0

d. 654.0

7. What is the minimum of the beds?

a. 91

b. 36

c. 30

d. 28

8. What is the maximum of the beds?

a. 654

b. 682

c. 37,703.6

d. 339,332.8

9. What is the count (or n) in this problem?

a. 10

b. 682

c. 140

d. 30

10. What is the interquartile range (IQR) of the beds?

a. 124.0

b. 91.0

c. 215.0

d. 42%

11. What is the variance of the beds?

a. 339,332.8

b. 1,964

c. 37,703.6

d. 194.2

12. What is the standard deviation of the beds?

a. 339,332.8

b. 1,964

c. 37,703.6

d. 194.2

13. What is the coefficient of variation of the beds?

a. 8%

b. 13%

c. 42%

d. 99%

14. What is the correct box-and-whisker plot for the beds?

Questions from Chapter 4

Are students who are good at math also good at statistics? Here is some data about imaginary students. We want to see if their math grade (x) is correlated with their statistics grade (y). Both grades are on a scale where 0.0 = F and 4.0 = A.

Student / Math Grade (x) / Statistics Grade (y)
Student 1 / 2.1 / 3.5
Student 2 / 3.4 / 4.0
Student 3 / 3.2 / 3.8
Student 4 / 1.5 / 2.5
Student 5 / 2.0 / 2.5

All questions in Chapter 4 section relate to these data. Round all answers to 1-digit past the decimal unless otherwise specified in the question.

1. Select the correct scattergram to correspond with the student grade data.

2. What is the strength and the direction of the correlation depicted in the scattergram?

a. Weak, positive

b. Strong, negative

c. Strong, positive

d. Weak, negative

3. What is the value of n?

a. 5

b. 10

c. 15

d. 20

4. What is the value of ∑x?

a. 12.2

b. 14.7

c. 3.2

d. 5.5

5. What is the value of ∑y?

a. 12.2

b. 3.8

c. 55.3

d. 16.3

6. What is the value of ∑xy?

a. 16.3

b. 32.5

c. 55.3

d. 42.0

7. What is the value of ∑x2?

a. 32.5

b. 55.3

c. 5.0

d. 45.3

8. What is the value of ∑y2?

a. 14.2

b. 55.3

c. 5.0

d. 45.3

9. What is the value of r?

a. -0.91

b. -0.07

c. 0.07

d. 0.91

10. What is the value of x-bar?

a. 1.4

b. 2.4

c. 3.4

d. 4.0

11. What is the value of y-bar?

a. 2.8

b. 3.3

c. 3.9

d. 1.5

12. What is the value of b?

a. 2.0

b. 0.8

c. 42.0

d. 2.3

13. What is the value of a?

a. 12.2

b. 3.3

c. 3.9

d. 1.4

14. What is the slope of the least squares line?

a. 0.8

b. 14.2

c. 13.0

d. 1.5

15. What is the y-intercept of the least squares line?

a. 1.4

b. 2.4

c. 3.4

d. 4.0

16. What is equation for the least squares line (2 points)?

a. y-hat = 42.3x + 32.5

b. y-hat = 2.3x – 14.2

c. y-hat = 0.8x +1.4

d. y-hat = 12x + 0.8

17. For each increment of x, what is the marginal change in y?

a. 1.4

b. 13

c. 0.8

d. 38.3

18. Using the least squares line equation, what is the predicted statistics grade for a student who gets a grade of 2.0 in math?

a. 4.0

b. 3.0

c. 2.0

d. 1.0

19. What is the coefficient of determination (r2)?

a. 75%

b. 83%

c. 91%

d. 100%

20. What is the percentage of variation in statistics grade can be explained by math grade?

a. 22%

b. 64%

c. 45%

d. 83%

21. Do you think this is a good prediction mode?

a. Yes, because the coefficient of determination is low.

b. Yes, because the coefficient of determination is high.

c. No, because the coefficient of determination is low.

d. No, because the coefficient of determination is high.