Question 1

In a study of the effects of humor on memory, Schmidt (1994) had participants read either humorous sentences or non-humorous sentences, and then he later tested participants' memory for the sentences.The control group in this experiment was:

Accepted Answer

The control group in an experiment serves as a baseline for comparison. In this case, the control group consisted of participants who were assigned non-humorous sentences, which allowed the researcher to compare the memory performance of participants who read humorous sentences to those who did not. The other options (B and C) do not accurately represent a control group in this study. Option D is not correct because every experiment should have a control group.

Question 2

Brent tosses a quarter 4 times and 3 times it comes up heads.The percentage of heads is:

Accepted Answer

The percentage of heads is found by dividing the number of times it came up heads by the total number of tosses and multiplying by 100. 
Percentage of heads = (Number of heads / Total tosses) x 100
In this case, the number of heads is 3 and the total number of tosses is 4. 
Percentage of heads = (3/4) x 100 = 75%

Question 3

A(n) _____ refers to each time a procedure is carried out.

Accepted Answer

A trial refers to each time a procedure is carried out. A success or failure is an outcome of the trial.

Question 4

What is the correct formula for calculating a probability?

Accepted Answer

The correct formula for calculating probability is to divide the number of successful outcomes (or trials) by the total number of possible outcomes (or trials). This gives us a decimal or fraction, which can then be converted to a percentage if needed. Option D correctly gives this formula.

Question 5

A(n) _____ refers to the result of a(n) _____.

Accepted Answer

An outcome is the result of a trial, where a trial is any procedure that can be infinitely repeated and has a well-defined set of possible outcomes.

Question 6

In a standard deck of playing cards, there is a total of 52 cards, 12 of which are face cards, such as queens, kings, and jacks.What is the formula for the expected relative-frequency probability of drawing a single face card from the deck of cards?

Accepted Answer

The formula for expected relative-frequency probability is:

Number of desired outcomes / Total number of possible outcomes

Out of the 52 cards, there are 12 face cards, so the number of desired outcomes is 12. The total number of possible outcomes is 52. Thus, the formula gives:

12/52 = 3/13

So the expected relative-frequency probability of drawing a single face card from the deck of cards is 3/13. Therefore, the best choice is B, which is the closest option to 3/13.

Question 7

When the outcome of one trial does not depend, in any way, on the outcome of previous trials, the events are said to be _____.

Accepted Answer

Independent events are those in which the outcome of one trial does not affect the outcome of future trials.

Question 8

Percentage is simply the _____ multiplied by 100.

Accepted Answer

A proportion is a part of a whole, and a percentage is simply the proportion multiplied by 100 to express it as a percentage. The other options are not directly related to finding a percentage.

Question 9

All of the recent children born into Jessica's family have been males, so there is a lot of pressure for her and her husband Matt to have the first granddaughter.In fact, everyone is sure that their first child will be a girl, because the family is due to have one! Unfortunately for their families, this logic is false because:

Accepted Answer

The sex of a child is determined independently of the sex of any previous children born, so the probability of having a girl is 50%. The expectation of having a granddaughter is based on an illusory correlation and not on the actual probability.

Question 10

Whereas _____ are not good at generating random numbers because of consideration of previous events, _____ have no memory for previous events and can therefore be unbiased.

Accepted Answer

The sentence is comparing two types of entities (researchers and students, computers and random numbers tables, humans and computers). The correct choice is C because it directly contrasts humans with computers, stating that humans have a memory for previous events (and are therefore not good at generating random numbers) while computers have no memory and can therefore be unbiased.

Question 11

Without many trials, one cannot determine true probabilities of events.However, over the long run, and numerous trials, the expected relative-frequency probability of events is very clear and predictable.This is known as the:

Accepted Answer

The law of large numbers states that as the number of trials increases, the relative-frequency probability of an event will approach its true probability. Therefore, option B is the best choice as it describes this phenomenon accurately. Options A, C, and D are not as specific or accurate in describing this concept.

Question 12

A trial refers to each time a procedure is:

Accepted Answer

A trial refers to each time a procedure is carried out. It does not necessarily refer to success or failure, or an expectation of success.

Question 13

A(n) _____ refers to the outcome for which one is trying to determine the probability.

Accepted Answer

The answer of A(n) _____ refers to the outcome for...

Question 14

Janice tosses a quarter 10 times and finds that 4 of the 10 times the quarter comes up heads and 6 of the 10 times the quarter comes up tails.What should Janice conclude?

Accepted Answer

In the long-term, the expected probability of getting heads or tails with a fair coin is 50% each (5/10), but with only 10 trials, the observed frequency can differ from the expected probability.

Question 15

Brent tosses a quarter 4 times and 3 times it comes up heads.The proportion of heads is:

Accepted Answer

The proportion of heads is calculated by dividing the number of heads by the total number of tosses. Here, it's 3 heads out of 4 tosses, which is 3/4 = 0.75.

Question 16

_____ refers to the occurrence of events over the long run, and _____ refers to the calculation of the number of successes divided by the number of trials.

Accepted Answer

Probability refers to the occurrence of events over the long run, and proportion refers to the calculation of the number of successes divided by the number of trials.

Question 17

Which of these are independent events?

Accepted Answer

The answer of Which of these are independent events?
...

Question 18

Two events are said to be independent events when:

Accepted Answer

In independent events, the probability of one event does not affect the probability of the other event occurring. Therefore, the correct answer is D, "the probability of one event is not influenced by the occurrence of the other event."

Question 19

Brent tosses a quarter 4 times and 3 times it comes up heads.The probability of heads is:

Accepted Answer

The probability of getting heads is calculated by dividing the number of times heads comes up by the total number of tosses. Here, heads comes up 3 times out of 4 tosses, so the probability is 3/4 or 0.75.

Question 20

A researcher is interested in the eventual divorce rates of people who live together before they get married compared to those who do not cohabitate before marriage.The researcher is particularly interested in the couples who cohabitate to see if that leads to higher divorce rates.In a sense, the couples who do not cohabitate are serving as the _____ group.

Accepted Answer

The group that does not cohabitate before marriage is serving as the control group, as it provides a baseline for comparison to the experimental group (those who do cohabitate). The control group allows the researcher to assess whether cohabitation has a significant effect on divorce rates.

Quiz 5: Sampling and Probability