University of North Carolina, Greensboro

ECO 25

1)A population is a subset of a sample.

1. 1. True
   2. False
2. When choosing a sample from a population, it is important to avoid doing so randomly.
   1. True
   2. False
3. A random variable always takes on the same number.
   1. True
   2. False
4. A random variable can take on a number of different possible values.
   1. True
   2. False
5. What is the expected value of a single die roll?
   1. 6
   2. 1

c. 3.5

d. 5

6. What is the standard deviation of a single die roll?

a. 1.71

b. 5

c.   2.92

d.   3.50

7. Using the above information, what is P(17)? a. 0.86

b.   0.06

c.   0.92

d. 5

8. Using the above information, what is C(17)? a. 0.86

b.   0.06

c.   0.92

d. 5

9. Using the above information, what is the probability that x is greater than or equal to 4 and less than 17?

a.   0.74

b.   0.86

c.   0.73

d.   0.79

10. How many possible values can the random variable x take on? a. 100

b. 216

c. 16

d. 12.5

11. How many ways can the sum of three dice add up to a 10? a. 12.5

b. 216

3. 50
4. 27

12. What is P(16)?

a. 98.15%

b. 16%

c. 2.78%

d. 4%

13. What is C(16)?

a. 98.15%

b. 16%

c. 2.78%

d. 4%

14. What is the expected value of the sum of three dice?
    1. 3
    2. 18

c. 10.5

d. 11

15. Identify the cumulative probability of getting an 18 or less on a roll of three dice, or C(18).

a. 100%

b. 0%

c.   18%

d.   50%

16. Identify the cumulative probability of getting a 10 or less on a roll of three dice, or C(10). a. 100%

b. 0%

c.   18%

d.   50%

17. Identify the cumulative probability of getting an 11 or more on a roll of three dice, or 1 – C(10).

a. 100%

b. 0%

c.   18%

d.   50%

18. Identify the cumulative probability of getting at least an 8 and at most a 13 on a roll of three dice, or C(13) – C(7).

a. 42.5%

b. 6%

c. 67.6%

d. 50%

19. Identify the cumulative probability of getting at least a 5 and at most a 16 on a roll of three dice, or C(16) – C(4).

a.   96.3%

b.   97.8%

c.   99.2%

d.   50.7%

20. Identify the cumulative probability of getting a more than 15 on a roll of three dice, or 1

– C(15).

a. 100%

b.   4.6%

c.   9.3%

d. 15%

21. Identify the cumulative probability of getting a less than 6 on a roll of three dice, or C(5). a. 100%

b.   4.6%

c.   9.3%

d. 15%

22. What percentage of the values the random variable can take on fall within 1 standard deviation of the expected value (note: the standard deviation is 2.958)?

a. 50%

b.   67.6%

c.   95.4%

d.   2.95%

23. What percentage of the values the random variable can take on fall within 2 standard deviations of the expected value (note: the standard deviation is 2.958)?

a.   99.9%

b.   32.8%

c.   96.3%

d.   5.91%

24. What is the cumulative probability of getting 7 or fewer heads in 10 coin flips, C(7)?

a.   0.945

b.   0.117

c.   0.171

d.   0.934

25. What is the cumulative probability of getting from 4 to 7 Heads in 10 coin flips, C(7) – C(3)?

a.   0.945

b.   0.774

c.   0.172

d.   0.376

26. What is the probability getting a 6 exactly seven times if we roll a single die ten times, P(7)?

a. 0.0002

b.   0.9998

c.   0.1666

d.   0.8333

27. What is the cumulative probability getting a 6 exactly seven or more times if we roll a single die ten times, 1 – C(6)?

a.   0.0003

b.   0.9998

c.   0.1666

d.   0.8333

28. What is the cumulative probability of getting from four and seven 6’s if we roll a single die ten times, C(7) – C(3)?

a.   0.0002

b.   0.0697

c.   0.9993

d.   0.3278

29. Suppose 57% of the students at UNCG are female. What is the probability of getting 40 or fewer males in a random selection of 100 UNCG students?

a.   0.692

b.   0.458

c.   0.570

d.   0.308

30. Suppose 57% of the students at UNCG are female. What is the probability of getting 20 or fewer males in a random selection of 50 UNCG students?

a.   0.390

b.   0.410

c.   0.430

d.   0.308

31. Suppose a manufacturing process results in one defective product per 100 units. What is the probability that there will be exactly eight defects in 1000 units produced?

a.   0.668

b.   0.331

c.   0.112

d.   0.012

32. Suppose a manufacturing process results in one defective product per 100 units. What is the probability that there will be eight or fewer defects in 1000 units produced?

a.   0.668

b.   0.331

c.   0.112

d.   0.012

33. Suppose a manufacturing process results in one defective product per 100 units. What is the probability that there will be fewer than eight defects in 1000 units produced?

a.   0.781

b.   0.331