Question 1

If an experiment has only two unique possible outcomes, then the probability of getting one of those two outcomes is 0.5.

Accepted Answer

This is known as the principle of equally likely outcomes, where the probability of getting one outcome is equal to the probability of getting the other outcome when there are only two possibilities. Therefore, the probability of getting one of those two outcomes is 0.5 or 50%.

Question 2

Suppose there are seven jelly beans in a bowl-three red and four blue. If a jelly bean is selected at random, what is the probability that it is blue?
A)2/7
B)3/7
C)4/7
D)5/7

Accepted Answer

The probability of selecting a blue jelly bean is the number of blue jelly beans divided by the total number of jelly beans, which is 4 blue out of 7 total, or 4/7.

Question 3

ABC College is using a new screening test to test its employees for TB. The following table shows the results of a pilot study:  Assuming that this result is representative of the college, estimate the probability that a randomly chosen employee who tested positive has TB.
A)89.1%
B)84.0%
C)13.3%
D)61.8%

Accepted Answer

D

Question 4

The _____ of a test is the probability that the test will give a negative result for a person who does not have the disease.
A)specificity
B)sensitivity
C)false positive
D)true negative

Accepted Answer

Specificity is the measure of a test's ability to correctly identify individuals who do not have the disease. It is represented by the true negative rate, which is the proportion of individuals without the disease who test negative.

Question 5

Suppose the inside bottom of a box is painted with three colors: one-third of the bottom area is blue, one-sixth is red, and one-half is yellow. If you toss a tiny pebble into the box without aiming, what is the probability the pebble will NOT land on the color blue?
A)2/3
B)1/3
C)5/6
D)1/2

Accepted Answer

The probability of the pebble landing on blue is 1/3. Therefore, the probability of it NOT landing on blue is 1 - 1/3 = 2/3.

Question 6

_____ probability is the probability that one event occurs given that another has occurred.
A)Recurrent
B)Disjunctive
C)Conditional
D)Predictive

Accepted Answer

Conditional probability is the probability of an event occurring given that another event has already occurred. It is usually denoted by P(A|B), where A is the event whose probability is being calculated and B is the event that has already occurred.

Question 7

ABC College is using a new screening test to test its employees for TB. The following table shows the results of a pilot study:  What percentage of the individuals in the study were false negatives?
A)75.9%
B)2.5%
C)13.3%
D)8.2%

Accepted Answer

The answer of ABC College is using a new screening...

Question 8

ABC College is using a new screening test to test its employees for TB. The following table shows the results of a pilot study:  For what percentage of the individuals in the study did the test return an INCORRECT result?
A)89.1%
B)34.0%
C)15.8%
D)10.8%

Accepted Answer

The answer of ABC College is using a new screening...

Question 9

Suppose you pick a marble from a box containing five red and seven blue marbles. You record the color and put the marble back in the box. What is the probability of getting a red marble both times if you do this twice?
A)5/12
B)4/11
C)25/144
D)5/33

Accepted Answer

The probability of picking a red marble on any one draw is 5/12, since there are five red marbles out of twelve total. Since you replace the marble after each draw, the two events of picking a red marble are independent, which means we can multiply their probabilities to get the probability of both events happening. Therefore, the probability of picking a red marble twice is (5/12) * (5/12) = 25/144.

Question 10

If an event can never occur, then the probability of the event is:
A)-1
B)0
C)0.5
D)1

Accepted Answer

The probability of an event can never be negative, so option A is incorrect. Similarly, the probability of an impossible event is zero, so option D is incorrect. Option C is incorrect as it implies that the event is equally likely to occur and not occur, which is not the case if the event can never occur. Therefore, the correct answer is option B, which indicates that the probability of the event is zero.

Question 11

A friend claims that it will rain today with probability 30% and tomorrow with probability four times as great as today. Which of the following is CORRECT?
A)The claim can be true because it is more likely to rain tomorrow if we have rain today.
B)The claim cannot be true because raining tomorrow is not guaranteed.
C)The claim can be true because it is possible to have rain tomorrow.
D)The claim cannot be true because any probability is between 0 and 1.

Accepted Answer

The probability for tomorrow would be 4 times 30%, which is 120%, exceeding the maximum probability limit of 100% (or 1). Thus, the claim violates the basic rule of probabilities being between 0 and 1.

Question 12

The prevalence of a disease in a given population is the percentage of the population that does NOT have the disease.

Accepted Answer

The prevalence of a disease in a given population is the percentage of the population that has the disease, not the percentage that does not have it.

Question 13

ABC College is using a new screening test to test its employees for TB. The following table shows the results of a pilot study:  What percentage of the individuals in the study who had TB tested negative?
A)3.2%
B)2.5%
C)16.0%
D)8.0%

Accepted Answer

Out of the 25 individuals who had TB in the study, 4 of them tested negative. Therefore, the percentage of individuals in the study who had TB and tested negative is (4/25)x100 = 16%.

Question 14

Michael and Surrey are planning to have three children. Assuming it is equally likely for a boy or a girl to be born, what is the probability that at least one of their children will be a boy?
A)1/8
B)3/8
C)5/8
D)7/8

Accepted Answer

The probability of having at least one boy equals 1 minus the probability of having all girls. The probability of having all girls is (1/2) x (1/2) x (1/2) = 1/8. Therefore, the probability of having at least one boy is 1 - 1/8 = 7/8.

Question 15

The probability of passing Professor Avila's math class is 65%, the probability of passing Professor Reid's biology class is 45%, and the probability of passing both is 25%. What is the probability of passing one or the other?
A)75%
B)85%
C)70%
D)110%

Accepted Answer

We can use the formula P(A or B) = P(A) + P(B) - P(A and B), where A is passing Avila's class and B is passing Reid's class. Plugging in the given probabilities, we get P(passing one or the other) = 0.65 + 0.45 - 0.25 = 0.85, or 85%. Therefore, the best choice is B.

Question 16

A city study finds that the probability of a car running a red light at a certain intersection during any given day is 9.6%. What is the probability that a car will NOT run the red light on a given day?
A)8.6%
B)96.0%
C)4.0%
D)90.4%

Accepted Answer

If the probability of a car running a red light is 9.6%, then the probability of a car NOT running the red light is 100% - 9.6% = 90.4%. Therefore, the answer is D, 90.4%.

Question 17

If each outcome of an experiment is equally likely, the _____ of an event is a fraction of favorable outcomes.
A)chances
B)odds
C)probability
D)success

Accepted Answer

If every outcome is equally likely in an experiment, then the probability of an event happening is the fraction of favorable outcomes. Chances and success are not incorrect, but probability is the most precise term in this scenario. Odds can also be used, but they are typically expressed as a ratio of favorable outcomes to unfavorable outcomes, rather than as a fraction.

Question 18

Suppose a coin is tossed three times and we count the total number of heads. How many possible outcomes are there?
A)3
B)4
C)5
D)6

Accepted Answer

The possible outcomes for the total number of heads when a coin is tossed three times are 0, 1, 2, or 3. This makes a total of 4 possible outcomes.

Question 19

The _____ of a test is the probability that the test will detect the disease in a person who does have the disease.
A)specificity
B)sensitivity
C)false positive
D)true negative

Accepted Answer

Sensitivity is the measure of a test's ability to correctly identify individuals who have the disease or condition being tested for, and is therefore the best choice for the given scenario. Specificity, on the other hand, is the measure of a test's ability to correctly identify individuals who do not have the disease, while false positive and true negative refer to specific types of errors a test can make.

Question 20

Suppose there are 15 jelly beans in a bowl-3 green, 5 blue, and 7 red. A jelly bean is selected at random. What is the probability the jelly bean is NOT blue?
A)1/3
B)2/3
C)7/15
D)8/15

Accepted Answer

The answer of Suppose there are 15 jelly beans in...

Quiz 5: Introduction to Probability

If an experiment has only two unique possible outcomes, then the probability of getting one of those two outcomes is 0.5.

Suppose there are seven jelly beans in a bowl-three red and four blue. If a jelly bean is selected at random, what is the probability that it is blue?

ABC College is using a new screening test to test its employees for TB. The following table shows the results of a pilot study: Assuming that this result is representative of the college, estimate the probability that a randomly chosen employee who tested positive has TB.

The _____ of a test is the probability that the test will give a negative result for a person who does not have the disease.

Suppose the inside bottom of a box is painted with three colors: one-third of the bottom area is blue, one-sixth is red, and one-half is yellow. If you toss a tiny pebble into the box without aiming, what is the probability the pebble will NOT land on the color blue?

_____ probability is the probability that one event occurs given that another has occurred.

ABC College is using a new screening test to test its employees for TB. The following table shows the results of a pilot study: What percentage of the individuals in the study were false negatives?

ABC College is using a new screening test to test its employees for TB. The following table shows the results of a pilot study: For what percentage of the individuals in the study did the test return an INCORRECT result?

Suppose you pick a marble from a box containing five red and seven blue marbles. You record the color and put the marble back in the box. What is the probability of getting a red marble both times if you do this twice?

If an event can never occur, then the probability of the event is:

A friend claims that it will rain today with probability 30% and tomorrow with probability four times as great as today. Which of the following is CORRECT?

The prevalence of a disease in a given population is the percentage of the population that does NOT have the disease.

ABC College is using a new screening test to test its employees for TB. The following table shows the results of a pilot study: What percentage of the individuals in the study who had TB tested negative?

Michael and Surrey are planning to have three children. Assuming it is equally likely for a boy or a girl to be born, what is the probability that at least one of their children will be a boy?

The probability of passing Professor Avila's math class is 65%, the probability of passing Professor Reid's biology class is 45%, and the probability of passing both is 25%. What is the probability of passing one or the other?

A city study finds that the probability of a car running a red light at a certain intersection during any given day is 9.6%. What is the probability that a car will NOT run the red light on a given day?

If each outcome of an experiment is equally likely, the _____ of an event is a fraction of favorable outcomes.

Suppose a coin is tossed three times and we count the total number of heads. How many possible outcomes are there?

The _____ of a test is the probability that the test will detect the disease in a person who does have the disease.

Suppose there are 15 jelly beans in a bowl-3 green, 5 blue, and 7 red. A jelly bean is selected at random. What is the probability the jelly bean is NOT blue?