Question 1

The probability that someone in the human population has blood type AB is about p = .08; the probability that someone has blood type O is about p = .25.Knowing that each individual can have one and only one blood type,what is the probability that a person has an AB or O blood type?

Accepted Answer

The probability of having either AB or O blood type can be calculated by adding the probabilities of each separately and then subtracting the probability of having both (which is 0 since an individual can only have one blood type). Therefore, P(AB or O) = P(AB) + P(O) - P(AB and O) = 0.08 + 0.25 - 0 = 0.33.

Question 2

By definition,the probability of an outcome or event is

Accepted Answer

The probability of an outcome or event is the proportion or fraction of times it is likely to occur and is particularly useful for predicting the likelihood of random events. Therefore, all of the choices are correct.

Question 3

A researcher has participants choose between three advertisements.She finds that 54 prefer Ad A,86 prefer Ad B,and 60 prefer Ad C. The probability or proportion of participants preferring Ad B is ______.

Accepted Answer

The probability or proportion is calculated by dividing the number of participants who prefer Ad B by the total number of participants: 86 / (54 + 86 + 60) = 86 / 200 = 0.43.

Question 4

The total number of possible outcomes for a random variable is referred to as

Accepted Answer

The sample space is the set of all possible outcomes for a random variable. Therefore, the total number of possible outcomes is referred to as the sample space.

Question 5

A gambler rolls a 3 with one roll of a single fair die.Given that the die was six-sided,what was the probability of rolling a 3 with one roll?

Accepted Answer

The probability of rolling a 3 with one roll of a fair six-sided die is 1/6. This is because there are six possible outcomes when rolling a single die (1, 2, 3, 4, 5, or 6), and only one of those outcomes is a 3. Therefore, the probability of rolling a 3 is 1 out of 6, or 1/6.

Question 6

Probability allows us to make predictions regarding:

Accepted Answer

Probability can be used to make predictions regarding any of these options, as they all involve some element of chance or uncertainty. Probability can help us understand the likelihood of a certain event occurring, the possible outcomes of a random process, or the distribution of values that a random variable might take on. Therefore, choice D is the best answer.

Question 7

A news poll showed that voters had no preference for either of three candidates.In this example,the probability of a vote for,say,Candidate A equals ______.

Accepted Answer

If the poll showed that voters had no preference for any of the three candidates, then the probability of a vote for any one of them would be equal. Since there are three candidates, each one would have a probability of 1/3. Therefore, the probability of a vote for Candidate A would be 1/3.

Question 8

If there are 13 heart cards in a deck of 52 cards,then what is the probability of selecting one heart card on a single draw from the deck of cards?

Accepted Answer

There are 13 heart cards out of 52 cards in the deck. So the probability of selecting one heart card on a single draw is 13/52 or simply 1/4. This is because the probability is calculated by dividing the number of desired outcomes by the total number of possible outcomes. So in this case, the number of desired outcomes (selecting one heart card) is 13, and the total number of possible outcomes (total number of cards in the deck) is 52.

Question 9

A researcher records the following data for the number of bids made on a sample of items sold at an auction.Based on the table,what was the probability that an item had seven bids made on it?

Accepted Answer

The answer of A researcher records the following data for...

Question 10

Which rule states that when two outcomes are mutually exclusive,the probability that either one of these outcomes will occur is the sum of their individual probabilities?

Accepted Answer

The additive rule states that when two outcomes are mutually exclusive, the probability that either one of these outcomes will occur is the sum of their individual probabilities. The multiplicative rule is used when finding the probability of two independent events occurring together, and is not applicable in this scenario. Therefore, the correct answer is choice A.

Question 11

The following are six random outcomes for a sample space: -1,-3,-3,-2,-5,and -6.What is the probability of selecting a -3 in this example?

Accepted Answer

There are a total of six possible outcomes and two of them result in selecting a -3, hence the probability of selecting a -3 is 2/6, which simplifies to 1/3 or approximately 0.33. Therefore, option B) is the correct choice.

Question 12

A researcher finds that 20 of 120 students failed an exam.In this case,the probability of failing this exam was ______.

Accepted Answer

Probability is calculated by dividing the number of outcomes in an event by the total number of possible outcomes. In this case, the probability of failing the exam is given by 20/120, which simplifies to 1/6 or about .17 (rounded to two decimal places). Therefore, the best choice is B, which corresponds to .17.

Question 13

In a game,the probability of winning money is p = .16,the probability of losing money is p = .54,and the probability of breaking even is p = .30.What is the probability of winning or losing money in this game?

Accepted Answer

The probability of winning or losing money is the sum of the probability of winning and the probability of losing: .16 + .54 = .70. Therefore, the correct answer is option C.

Question 14

A researcher determines that the probability of winning a new game is p = .32.Assuming winning and losing are mutually exclusive events,what is the probability of winning and losing the new game?

Accepted Answer

Winning and losing are mutually exclusive events, meaning they cannot happen at the same time. Therefore, the probability of both winning and losing simultaneously is 0.

Question 15

A researcher determines the probability that a research study will reveal something new is p = .80.What is the probability that the study will reveal something new or not reveal something new?

Accepted Answer

The probability of either revealing something new or not revealing something new is always 1, as the study can only have one outcome. Therefore, the probability is 1.

Question 16

A therapist goes through her records and finds that 200 of her 400 patients showed significant improvement in mental health over the past year.Hence,the probability of her patients showing significant improvement in mental health is ______.

Accepted Answer

The probability of her patients showing significant improvement in mental health is calculated by dividing the number of patients who showed significant improvement in mental health over the past year by the total number of patients, which is:

200/400 = 0.50 or 50%

Therefore, the best choice is B.

Question 17

Which of the following is NOT a characteristic of probability?

Accepted Answer

Probability is most useful for describing uncertain events or outcomes, not fixed events.

Question 18

A researcher visits a population of 1,200 local residents to determine the proportion of local residents who support a new smoking ban.In this case,the sample space is

Accepted Answer

The sample space is the set of all possible outcomes of a statistical study or experiment. In this case, the researcher is visiting the entire population of 1,200 local residents, so the sample space is equal to the population of 1,200 local residents. It is not equal to the number of residents who support the new smoking ban (as this is only one possible outcome), the number of local residents who smoke (which is not necessarily related to the research question), or unknown (as we have sufficient information to define the sample space).

Question 19

Two outcomes are said to be mutually exclusive when

Accepted Answer

Mutually exclusive outcomes cannot occur at the same time, so their joint probability is zero.

Question 20

The proportion or fraction of times an outcome is likely to occur is referred to as

Accepted Answer

The definition given perfectly describes probability, which is the measurement or evaluation of the likelihood of an event occurring. B and C are related to probability, but they are not the precise definition. D is an abstract concept and is not related to probability.

Quiz 5: Probability