QM 213 Midterm

4. Which of the following is that branch of statistics that deals with the selection and use of sample data to produce information about the larger population from which the sample was selected: a. inferential statistics b. descriptive statistics c. statistical inference d. report generation e. none of the above

Ans: A/inferential statistics

1. Statistics is the art and science of collecting, analyzing, interpreting, and presenting data in an effort to transform that data into useful information. a. True b. False

Ans: A True

2. Descriptive statistics focuses on summarizing data while inferential statistics deals with the selection and use of sample data to produce information about the larger population from which the sample was selected. a. True b. False

Ans: A/ True

9. The empirical rule states that approximately 95.9% of values in a data set will be within two standard deviations of the mean if the data follows a bell-shaped curve. A. True B. False

Ans: A/ True

6. Which of the following best describes the role of probability theory: a. it is the link between descriptive statistics and inferential statistics b. it is the link between statistics and data c. it explains the role of chance in everyday events d. it is used to describe various distributions of data e. all of the above

Ans: A/ it is the link between descriptive statistics and inferential statistics

15. Below is a table showing the five department heads in Carlton-Manning's San Jose (CA) and Utica (NY) regional offices, along with each department head's forecast of sales in the upcoming quarter. One person from the group will be randomly chosen to make a sales presentation. Determine the simple probability of randomly selecting a person who forecasts a decrease in sales. Nathan Fiona George Sachiko Hugo Office San Jose Utica Utica San Jose San Jose Forecast Increase Decrease Decrease Increase Decrease a. .4 b. .6 c. .125 d. .25 e. .3

Ans: B/ 6

12. The correlation of two variables, x and y, is -0.95. This means that: a. as x increases, y tends to increase, and the relationship between the two is nearly linear. b. as x decreases, y tends to increase, and the relationship between the two variables is nearly linear. c. as x increases, y tends to decrease, and the slope of the relationship between x and y is approximately -0.05. d. an increase in x causes a fall in y. e. none of the above

Ans: B/ as x decreases, y tends to increase, and the relationship between the two variables is nearly linear.

3. Which of the following is that branch of statistics that focuses on summarizing and presenting data: a. inferential statistics b. descriptive statistics c. statistical inference d. report generation e. none of the above

Ans: B/ descriptive statistics

7. When looking at the shape of a distribution, which of the following best describes positive skewness? a. the distribution is evenly split into two identical halves b. the distribution has an elongated tail in the right-hand direction c. the distribution has an elongated tail in the left-hand direction d. the distribution has a very steep single peak e. the distribution has two separate peaks with a valley in between

Ans: B/ the distribution has an elongated tail in the right-hand direction

14. An experiment consists of four outcomes with P(E1) = 0.2, P(E2) = 0.25, and P(E3) = 0.35. The probability of P(E4) is: a. 0.50 b. 0.90 c. 0.20 d. 0.10 e. none of the above

Ans: C/ 0.20

16. Josh has been given two assignments, assignment A and assignment B. He estimates that the chance of getting a passing grade on assignment A is 60% and the chance of getting a passing grade on assignment B is 50%. Assuming that assignment grades are statistically independent, how likely is it that Josh gets a passing grade on both assignments? a. 20% b. 50% c. 30% d. 10% e. 70%

Ans: C/ 30%

8. Which of the following distribution shapes is one in which the distribution is split into two identical halves? a. positively skewed b. negatively skewed c. symmetric d. bimodal e. flat

Ans: C/ Symmetric

13. An experiment consists of four outcomes with P(E1) = 0.2, P(E2) = 0.3, and P(E3) = 0.4. The probability of P(E4) is: a. 0.50 b. 0.90 c. 0.02 d. 0.10 e. none of the above

Ans: D/ 0.10

10. Which of the following approaches can be used to identify outliers? a. 1.5*IQR (interquartile range) b. empirical rule c. z-score d. all of the above e. none of the above

Ans: D/ All of the above

5. A statistics professor asked students in a class their height. On the basis of this information, the professor states that the average height of all the students in the university is 67.3 inches. This is an example of: a. a census b. descriptive statistics c. an experiment d. statistical inference e. none of the above

Ans: D/ Statistical inference

11. Which of the following best describes the correlation coefficient? a. it is a standardized measure and can take on values from -1 to +1 b. it is the covariance of two variables divided by the product of the individual standard deviations c. values near -1 represent a strong negative linear relationship d. for samples it is denoted by rxy e. all of the above

Ans: E/ All of the above

19. Which of the following is a condition for a binomial probability experiment? a. the experiment involves a number of "trials," represented by n. b. only two outcomes are possible on each of the trials. c. the trials are statistically independent. d. the probability of success, p, on any one trial remains constant throughout the experiment. e. all of the above

Ans: E/ All of the above

20. Which of the following is a condition for a Poisson probability experiment? a. we need to be assessing the probability for the number of occurrences of some event per unit time, space, or distance. b. the average number of occurrences per unit of time, space, or distance is constant. c. the average number of occurrences per unit of time, space, or distance is proportionate to the size of the unit of time, space, or distance involved. d. individual occurrences of the event are random and statistically independent. e. all of the above

Ans: E/ All of the above

17. The binomial probability function is composed of two parts, the first of which computes the probability of each of the ways in which the x successes in n trials can occur. Ans: True/False

Ans: False

18. One of the conditions for a Poisson experiment is that the average number of occurrences per unit of time, space, or distance is constant and proportionate to the size of the unit of time, space, or distance involved. True False

Ans: True