Chapter 5 Stat

Suppose that A and B are independent events with and .is

B. 0.12.

Use Scenario 5-5. P(A B) =

D. 5/6.

An assignment of probabilities must obey which of the following?

d All three of the above

. You are playing a board game with some friends that involves rolling two six-sided dice. For eight consecutive rolls, the sum on the dice is 6. Which of the following statements is true?

d The probability of rolling a 6 on the ninth roll is the same as it was on the first roll.

A stack of four cards contains two red cards and two black cards. I select two cards, one at a time, and do not replace the first card selected before selecting the second card. Consider the events A = the first card selected is red B = the second card selected is red The events A and B are .

d not independent, not disjoint

The collection of all possible outcomes of a random phenomenon is called

d the sample space .

Use Scenario 5-2. The probability that you do not draw a red candy is

d .8

Event A occurs with probability 0.8. The conditional probability that event B occurs, given that A occurs, is 0.5. The probability that both A and B occur

B. is 0.4.

Use Scenario 5-13. If two students are selected at random, what is the probability that neither of them has a dog or a cat?

C. 0. 548

Use Scenario 5-5. P(A B) =

C. 1/3.

Use Scenario 5-4. The probability that you win at least $1 both times is

C. 1/4.

Use Scenario 5-7. The proportion of adults for which the test would be positive is

D. 0.02097.

Use Scenario 5-8. Find and write in words what this expression represents.

D. 0.30; The probability the student ate breakfast, given she is female.

Use Scenario 5-11. If you know the person that has been randomly selected is left-handed, what is the probability that they prefer to communicate with friends in person?

D. 0.382

Use Scenario 5-10. The probability that the student takes neither Chemistry nor Spanish is

D. 0.4

. Suppose that A and B are independent events with and . is:

D. 0.52.

Use Scenario 5-7. If a randomly selected person is tested and the result is positive, the probability the individual has the disease is

E. 0.047.

Use Scenario 5-9. What is the probability that the person is a woman, given that she said "Yes?"

E. 0.575

Event A has probability 0.4. Event B has probability 0.5. If A and B are disjoint, then the probability that both events occur is

a 0.0

You read in a book on poker that the probability of being dealt three of a kind in a five-card poker hand is 1/50. What does this mean?

a If you deal thousands of poker hands, the fraction of them that contain three of a kind will

. Use Scenario 5-3. The events A = the next two babies are boys, and B = the next two babies are girls are

a disjoint

Students at University X must have one of four class ranks—freshman, sophomore, junior, or senior. At University X, 35% of the students are freshmen and 30% are sophomores. If a University X student is selected at random, the probability that he or she is either a junior or a senior is

b 35%

If the knowledge that an event A has occurred implies that a second event B cannot occur, the events are said to be

b disjoint

Which of the following statements is not true?

c If two events are independent, then they must be mutually exclusive.

Use Scenario 5-2. The probability of drawing a yellow candy is

c .3

Use Scenario 5-2. The probability that you draw either a brown or a green candy is

c .4

When two coins are tossed, the probability of getting two heads is 0.25. This means that

d in the long run two heads will occur on 25% of all tosses.

You want to use simulation to estimate the probability of getting exactly one head and one tail in two tosses of a fair coin. You assign the digits 0, 1, 2, 3, 4 to heads and 5, 6, 7, 8, 9 to tails. Using the following random digits to execute as many simulations as possible, what is your estimate of the probability? 19226 95034 05756 07118

d 6/10

Use Scenario 5-3. The probability that at least one of the next three babies is a boy is

e .875

Ignoring twins and other multiple births, assume that babies born at a hospital are independent random events with the probability that a baby is a boy and the probability that a baby is a girl both equal to 0.5. ____ 17. Use Scenario 5-3. The probability that the next five babies are girls is

e 0.03125.

Use Scenario 5-11. Which of the following statements supports the conclusion that the event "Right-handed" and the event "Online" are not independent?

e 51/60 = 166/200

Use Scenario 5-8. What is the probability that the student had breakfast?

C. 0.50

You ask a sample of 370 people, "Should clinical trials on issues such as heart attacks that affect both sexes use subjects of just one sex?" The responses are in the table below. Suppose you choose one of these people at random Yes No Male 34 105 Female 46 185 ____ 38. Use Scenario 5-9. What is the probability that the person said "Yes," given that she is a woman?

A. 0.20

A student is chosen at random from the River City High School student body, and the following events are recorded: M = The student is male F = The student is female B = The student ate breakfast that morning. N = The student did not eat breakfast that morning. The following tree diagram gives probabilities associated with these events. ____ 34. Use Scenario 5-8. What is the probability that the selected student is a male and ate breakfast?

A. 0.32

In a particular game, a fair die is tossed. If the number of spots showing is either four or five, you win $1. If the number of spots showing is six, you win $4. And if the number of spots showing is one, two, or three, you win nothing. You are going to play the game twice. ____ 26. Use Scenario 5-4. The probability that you win $4 both times is

A. 1/36.

In a certain town, 60% of the households have broadband internet access, 30% have at least one high-definition television, and 20% have both. The proportion of households that have neither broadband internet nor high-definition television is:

C. 30%.

Suppose we roll two six-sided dice--one red and one green. Let A be the event that the number of spots showing on the red die is three or less and B be the event that the number of spots showing on the green die is three or more. ____ 28. Use Scenario 5-5. The events A and B are

C. independent.

3. Use Scenario 5-11. What is the probability that the student chosen is left-handed or prefers to communicate with friends in person? A. 0.065 B. 0.17 C. 0.425 D. 0.53 E. 0.595

D. 0.53

Use Scenario 5-8. Given that a student who ate breakfast is selected, what is the probability that he is male?

D. 0.64

Use Scenario 5-10. Find the value of and describe it in words.

D. 0.6; The probability that the student takes either chemistry or Spanish, or both.

Use Scenario 5-13. If a single student is selected at random, what is the probability associated with the union of the events "has a dog" and "does not have a cat?"

D. 0.9

. Use Scenario 5-13. If a single student is selected at random and you know she has a dog, what is the probability she also has a cat?

E. 0.75

Event A occurs with probability 0.3. If event A and B are disjoint, then

c .7

A basketball player makes 160 out of 200 free throws. We would estimate the probability that the player makes his next free throw to be

c 0.80

I toss a penny and observe whether it lands heads up or tails up. Suppose the penny is fair, i.e., the probability of heads is 1/2 and the probability of tails is 1/2. This means that

c if I flip the coin many, many times the proportion of heads will be approximately 1/2, and

A basketball player makes 75% of his free throws. We want to estimate the probability that he makes 4 or more frees throws out of 5 attempts (we assume the shots are independent). To do this, we use the digits 1, 2, and 3 to correspond to making the free throw and the digit 4 to correspond to missing the free throw. If the table of random digits begins with the digits below, how many free throw does he hit in our first simulation of five shots? 19223 95034 58301

e 5

Here is an assignment of probabilities to the face that comes up when rolling a die once: Outcome 1 2 3 4 5 6 Probability 1/7 2/7 0 3/7 0 1/7 Which of the following is true?

e This is a legitimate assignment of probability