statistics. 20 questions
ASSIGNMENT #3
1. The collection of all possible sample points in an experiment is
|
a. |
the sample space |
|
b. |
a sample point |
|
c. |
an experiment |
|
d. |
the population |
2. From a group of six people, two individuals are to be selected at random. How many possible selections are there?
|
a. |
12 |
|
b. |
36 |
|
c. |
15 |
|
d. |
8 |
3. Two events, A and B, are mutually exclusive and each have a nonzero probability. If event A is known to occur, the probability of the occurrence of event B is
|
a. |
one |
|
b. |
any positive value |
|
c. |
zero |
|
d. |
any value between 0 and 1 |
4. If A and B are independent events with P(A) = 0.65 and P(A ∩ B) = 0.26, then, P(B) =
|
a. |
0.400 |
|
b. |
0.169 |
|
c. |
0.390 |
|
d. |
0.650 |
5. If P(A) = 0.4, P(B | A) = 0.35, P(A B) = 0.69, then P(B) =
|
a. |
0.14 |
|
b. |
0.43 |
|
c. |
0.75 |
|
d. |
0.59 |
|
|
|
6. Since the sun must rise tomorrow, then the probability of the sun rising tomorrow is
|
a. |
much larger than one |
|
b. |
zero |
|
c. |
infinity |
|
d. |
none of these alternatives is correct |
7. Assume your favorite football team has 2 games left to finish the season. The outcome of each game can be win, lose or tie. The number of possible outcomes is
|
a. |
2 |
|
b. |
4 |
|
c. |
6 |
|
d. |
9 |
8. If a coin is tossed three times, the likelihood of obtaining three heads in a row is
|
a. |
0.000 |
|
b. |
0.500 |
|
c. |
0.875 |
|
d. |
0.125 |
9. If A and B are independent events with P(A) = 0.4 and P(B) = 0.6, then P(A ∩ B) =
|
a. |
0.76 |
|
b. |
1.00 |
|
c. |
0.24 |
|
d. |
0.20 |
10. An automobile dealer has kept records on the customers who visited his showroom. 40% of the people who visited his dealership were female. Furthermore, his records show that 35% of the females who visited his dealership purchased an automobile, while 20% of the males who visited his dealership purchased an automobile. Given that an automobile is purchased at the dealership, what is the probability that the customer is a female?
|
a. |
0.080 |
|
b. |
0.550 |
|
c. |
0.400 |
|
d. |
0.538 |
11. A bank gives a test to screen prospective employees. Among those who perform their jobs satisfactorily, 65% pass the test. Among those who do not perform satisfactorily, 25% pass the test. According to the bank’s records, 90% of its employees perform their jobs satisfactorily. What is the probability that a prospective employee who passed the test will not perform satisfactorily?
|
a. |
0.028 |
|
b. |
0.041 |
|
c. |
0.025 |
|
d. |
0.585 |
12. How many committees consisting of 3 female and 5 male students can be selected from a group of 5 female and 8 male students?
|
a. |
200 |
|
b. |
20,160 |
|
c. |
396 |
|
d. |
560 |
|
e. |
66 |
13. Consider the experiment of tossing a coin three times and recording the outcome. Compute the total number of possible outcomes. You might also want to list the possible outcomes – this will help you with the next several problems.
|
a. |
4 |
|
b. |
8 |
|
c. |
6 |
|
d. |
10 |
14. Refer to question 13. Define an event A = {HHH, TTT, HTH} and an event B = {HHH, HTH, HHT, TTH}. Compute P(A) and P(B).
|
a. |
P(A) = 3/8; P(B) = 1/2 |
|
b. |
P(A) = 1/2; P(B) = 1/2 |
|
c. |
P(A) = 3/4; P(B) = 1/2 |
|
d. |
P(A) = 1/4; P(B) = 1/4 |
15. Refer to question 14. Compute P(AB).
|
a. |
1/4 |
|
b. |
1/2 |
|
c. |
3/4 |
|
d. |
5/8 |
|
e. |
1 |
16. Refer to question 14. Compute P(BA).
|
a. |
1/4 |
|
b. |
1/3 |
|
c. |
2/3 |
|
d. |
3/4 |
|
e. |
1 |
17. Refer to question 14. Are events A and B independent?
|
a. |
yes |
|
b. |
no |
18. Refer to question 14. Are events A and B mutually exclusive?
|
a. |
yes |
|
b. |
no |
19. If a six-sided die is tossed two times, the probability of obtaining two "4s" in a row is
|
a. |
1/6 |
|
b. |
1/36 |
|
c. |
1/96 |
|
d. |
1/216 |
20. Events A and B are mutually exclusive. Which of the following statements is also true?
|
a. |
A and B are also independent. |
|
b. |
P(A B) = P(A)P(B) |
|
c. |
P(A B) = P(A) + P(B) |
|
d. |
P(A ∩ B) = P(A) + P(B) |
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