STAT3321 – Exam 1 – Spring, 2009 – White Exam - (In parentheses are the matching question number on the blue exam. Note: the answers are in different order)
1.(4.). You believe that your grade on this exam (as a numeric value), Y, linearly depends on the number of hours you study, X. The slopeof the line has the following meaning:
a. the variation in the exam grade as a percent of the variation in number of hours studied
b. the grade that you will get when you do not study
c. the distribution of the grade and hours studied
d. the change in the average grade for every hour studied
2.(24.) If the exam grades have a standard deviation of 8.9, this implies that
a. the class average is 8.9 points give or take 8.9 points
b. the typical person in the class will miss the class average by 8.9 points
c. every person in the class will miss the class average by 8.9 points
d. the variation of qualitative data is 8.9 points
3.(9.)If the proportion of students who make an A is the same as the probability of choosing a person who gets an A then the data is collected using a(n)
a.ogive
b. random sample
c. judgement sample
d. a typical error
4.(15.) In a city 10% of the cabs are green and 90% are yellow. An accident occurred at night and a witness identified the cab as green. The witness was tested under similar conditions. If a cab was green, then 85% of the time the witness correctly identified it as green and similarly if the cab was yellow, 85% of the time the witness correctly identified it as yellow. Given this information what is the probability of the cab being green if the witness has identified the cab as green?
a. 0.94
b. 0.85
c. 0.39
d. none of the above
5. (2.) Which of the following is NOT one of basic building blocks of statistics?
a. statistics always gives you correct answers.
b. the typical error of a statistics depends on how many obserations you have collected and on how much variability you have in the data.
c. sample statistics tend to miss the actual value of parameters.
d. a random sample is needed to reduce bias
6.(21.) If Pr(A) = 0.2, Pr (B) = 0.50, and Pr(A and B) = 0.10, then the events A and B are
a. independent
b. mutually exclusive
c. average
d. not independent
7. (5) Scatterplots are used to
a. plot frequencies
b. examine the relationship between two quantitative variables
c. plot percentages
d. examine the relationship between two qualitative variables
8. (3) The empirical rule does NOT require you to have
a. the value of the mean of a population
b. a symmetric mound-shaped population of data
c. the value of the standard deviation of a sample
d. the value of the standard deviation of a population
9. (8) Which of the following is a data type you would see in a row of an Excel spreadsheet?
a. all of the others are types of data
b. interval data
c. discrete data
d. nominal data
10. (23) On the chart to the right, what is the value of the 80th percentile?
a. 60
b. can not be determined
c. 90
d. 45
11. (22) The number of people requesting Diet Coke (or not) at a restaurant is assumed to be a binomial random variable. If the probability of anyone person requesting a Diet Coke is 0.13, what is the probability that 8 of the next 10 people will request Diet Cokes? Choose the appropriate substitution.
a.
b.
c.
d.
12. (18.)You have 5 mutually exclusive events A1, A2, A3, A4 and A5. If Pr(A1) = 0.10, Pr(A2) = 0.20, Pr(A3) = 0.30, Pr(A4) = 0.40, then what is the probability of A5? (Hint: read this carefully)
a. -0.50
b. 0.50
c. 0.25
d. 0
13. (11.) To determine the relationship between the major of an undergraduate student and the major of the same student in graduate school, you would use a(n)
a. contingency table
b. ogive
c. scatterplot
d. the slope
14. (16.) What is the variance of the following population of numbers? 1, 1, 9, 2, 2
a. 5
b. 11.5
c. 3.39
d. 9.2
15.(13.) Suppose the amount of money spent per person at a restaurant follows a bell-shaped symmetric distribution with a population average of 25 dollars. You decide to take a random sample of 10 people from this population and ask each of them “Did you spend more than $25?” What is the probability of finding that exactly 7 of the 10 answered “Yes”?
a.0.500
b.0.117
c. 0.353
d. can not be determined
16. (19.) Given the following table, find the Pr (B1 or A1)
A1 / A2 / TotalB1 / 4 / 9 / 13
B2 / 12 / 16 / 28
B3 / 24 / 35 / 59
Total / 40 / 60 / 100
a. 0.04
b. 0.49
c. 0.31
d. none of the above
17. (17.) You find that68% of the sample variation in salesis associated with variation in advertising. This is the meaning of the
a. the coefficient of determination
b. slope.
c. empirical rule
d. the median
18. (10.) If Pr(A) = 0.90, Pr(B|A) = 0.5, Pr(Ac)=0.10 and Pr(B|Ac) = 0.6 then the Pr(A|B)
a. 0.33
b. 0.45
c. 0.88
d. none of the above
19. (6.) If n=15 and p=0.30, what is the probability of getting one or more successes?
a. 0.995
b. 0.301
c. 0.200
d. none of the other answers are correct
20. (20.) You plan to measure the amount of cash you have at the end of each month. You take a random sample of 18 months from the last 5 years. Which of the previous is an example of qualitative data?
a. the amount of cash
b. the value 5.
c. the random sample
d. the month
21. (12.) You wish to measure net income and sales for companies in the northeast. You decide to select 7 of these companies. Which of the following is an example of a parameter that would interest you?
a. the average net income of all companies in the northeast.
b. the number of net incomes in the sample of companies in the northeast.
c. the population of all companies in the northeast
d. the average net income of the seven companies in the northeast.
22. (14.) If a population of data is mound-shaped symmetric with a mean of 20 and a standard deviation of 2, 95% of all values will fall between
a. 18 and 22
b. 14 and 26
c. 20 and 22
d. 16 and 24
23. (7.) Experiments are data collection types that …
a. are based on a person’s decision about the correctness of collecting the observation
b. select every individual or item from the frame (a list) such that each has an equal chance of being selected
c. are based on questionnaires that ask people’s opinions.
d. in many cases allow cause-and-effect relationship to be established
24. (1. ) What is the mean and symbol of the following sample of numbers? 1, 1, 39, 2, 2
a. = 9
b. x = 39
c. = 39
d. x = 9
25.(25.) Following the instructions below, choose an answer
a. Do not choose this one
b. Do not choose this one
c. Choose this one. ←
d. Do not choose this one
Answers
1D
2B
3B
4C
5A
6A
7B
8C
9A
10A
11A
12D
13A
14D
15B
16B
17A
18C
19A
20D
21A
22D
23D
24D
25C