Test questions 230

Last summer my June, July, and August phone bills were $20, $30, and $100 respectively. What was my average monthly bill for the summer? a. $75 b. $60 c. $50 d. $30

$50

For a population with µ = 80 and σ = 10, what is the z score corresponding to X = 85? a. +1.00 b. +5.00 c. +2.00 d. +0.50

+0.50

For a population with σ = 4, an individual with a deviation score of +2 would have a z-score of _____. a. +8.00 b. +2.00 c. Cannot be determined without knowing the population mean d. +0.50

+0.50

In a distribution with μ = 60 and σ = 10 a score of X = 45 is below the mean by exactly 1.50 standard deviations, which means that it corresponds to a z-score of z = −1.50. For this same distribution, what is the z-score corresponding to X = 70? a. z = +0.50 b. z = +1.00 c. z = +0.25 d. z = +2.50

+1.00

Which of the following deviation scores corresponds to the score that is farthest away from the mean? a. 0 b. -5 c. 5 d. -10

-10

In a population of N = 5 scores, the first four scores each have a deviation of +2. What is the deviation for the 5th score? a. −2 b. +8 c. −8 d. +2

-8

For a population that has a mean of µ = 24 with a standard deviation of σ = 4 and N = 10, what is the value for ∑(X - µ)? a. 0 b. 2.5 c. 400 d. 16

0

What is the variance for the following population? Scores: 5, 5, 5, 5 a. 4 b. 5 c. 1 d. 0

0

The proportion of a normal distribution that corresponds to values less than z = 1.00 is p = 0.8413. Base on this information, what is the proportion that corresponds to values less than z = −1.00? a. −0.1587 b. −0.8413 c. 0.1587 d. 0.8413

0.1587

What is the proportion associated with X = 3? X f 5 1 4 2 3 4 2 1 1 2 a. 0.20 b. 0.30 c. 0.10 d. 0.40

0.40

For the following frequency distribution, how many individuals had a score of X = 2? x f 5 1 4 2 3 4 2 1 1 2 a. either 1 or 4 b. 1 c. 2 d. 4

1

On an exam with a mean of µ = 70, you have a score of X = 75. Which value for the standard deviation would give you the highest position within the class? a. 10 b. 5 c. 1 d. cannot determine from the information given

1

The following population has a mean of μ = 5. What is the standard deviation for this population? Scores: 4, 4, 6, 6 a. 2 b. 10 c. 0 d. 1

1

A skewed distribution typically has _____ tail(s) and a normal distribution has ____ tail(s). a. 2, 2 b. 1, 1 c. 2, 1 d. 1, 2

1, 2

For a distribution of exam scores with μ = 50, which value for the standard deviation would give the highest grade to a score of X = 45? a. σ = 10 b. σ = 1 c. σ = 5 d. σ = 2

10

What is the value of ∑X for the following scores: 3, 2, 5? a. 3.33 b. 30 c. 10 d. 3

10

Which set of scores has the least amount of variability? a. 11, 17, 31, 53 b. 5, 11, 42, 22 c. 27, 105, 10, 80 d. 145, 143, 145, 147

145, 143, 145, 147

An introductory psychology class has 9 freshman males, 15 freshman females, 8 sophomore males, and 12 sophomore females. What is the probability of randomly selecting a male from this group? a. 8/20 b. 17/44 c. 17/20 d. 9/24

17/44

For a sample of n = 10 scores, how many scores are used to compute the range? a. 9 b. all 10 c. 3 d. 2

2

After 5 points are added to every score in a distribution, the mean is calculated and found to be µ = 30. What was the value of the mean for the original distribution? a. Cannot be determined from the information given. b. 35 c. 25 d. 30

25

A population of scores has µ = 42. In this population, an X value of 40 corresponds to z = −0.50. What is the population standard deviation? a. 2 b. −4 c. 4 d. −2

4

For the following scores, what is the frequency corresponding to X = 3? Scores: 1, 4, 3, 2, 3, 1, 1, 5, 3, 3, 2, 4 a. 4 b. 2 c. 3 d. 1

4

A sample has a mean of M = 30. If one score with a value of X = 10 is removed from the sample, what effect will it have on the sample mean? a. The sample mean will decrease. b. The sample mean cannot be determined from the information given c. The sample mean will increase. d. The sample mean will remain the same.

40-41

A set of scores ranges from a high of X = 67 to a low of X = 23. If these scores are organized in a grouped frequency distribution table with an interval width of 5 points, then roughly how many intervals will be needed? a. 45 b. 8-9 c. 44 d. 13-14

44

n a grouped frequency distribution one interval is listed as 50-54. What are the real limits of this interval? a. 50.5 and 54.5 b. 49.5 and 54.5 c. 50.5 and 53.5 d. 50 and 54

49.5 and 54.5

In a grouped frequency distribution one interval is listed as 50-54. What is the width of this interval? a. 4 points b. 54 points c. 3 points d. 5 points

5 points

The most commonly used measure of central tendency is _____. a. the range b. the mode c. the mean d. the median

5(9) = 45

For a sample of n = 8 scores, the sum of the squared deviations is 50. If these same scores were a population, then what value would be obtained for the sum of squared deviations for the population? a. 50 b. greater than 50 c. less than 50 d. impossible to determine without additional information

50

For a normal distribution with µ = 100 and σ = 10, what is the probability of selecting a score less than X = 85? a. -6.68% b. 6.68% c. 93.32% d. 43.32%

6.68%

A sample of n = 25 scores has a mean of M = 11. If each score in the sample is multiplied by 6, then what is the mean for the new sample? a. 6 b. 150 c. 11 d. 66

66

What is the mean for the following set of scores? Scores: 1, 6, 10, 11 a. 7 b. 14 c. 4 d. 8

7

For a population with µ = 60 and σ = 8, what is the X value corresponding to z = 1.50? a. 61.5 b. 90 c. 72 d. 12

72

A population of scores has σ= 20. In this population, a score of X = 80 corresponds to z = +0.25. What is the population mean? a. 70 b. 85 c. 90 d. 75

75

A sample of n = 20 scores ranges from a high of X = 10 to a low of X = 3. If these scores are placed in a frequency distribution table, how many rows will the table have? a. 8 b. 20 c. 7 d. 10

8

What is the median for the following set of scores? Scores: 1, 3, 9, 10, 22 a. 9.5 b. 6 c. 11 d. 9

9

For a population with µ = 100 and σ = 20, what is the X value corresponding to z = −0.25? a. 97.5 b. 95 c. 92.5 d. 99.75

95

Which of the following is a characteristic of an experimental research study? a. It requires that other variables be controlled. b. Its goal is to demonstrate a cause-and-effect relationship. c. All of the other options are characteristics of an experiment. d. It requires the manipulation of one variable.

All of the other options are characteristics of an experiment.

Which of the following samples would have the largest value for sample variance? a. 51, 53, 55 b. All the samples would have exactly the same variance. c. 1, 3, 5 d. 11, 13, 15

All the samples would have exactly the same variance

For a sample with a mean of M = 70, what is the z-score corresponding to a score that is located 10 points below the mean? a. +1 b. −10 c. −1 d. Cannot answer without knowing the standard deviation

Cannot answer without knowing the standard deviation

What is the lowest score in the following distribution? X f 70-74 3 65-69 4 60-64 8 55-59 2 50-54 1 a. X = 45 b. Cannot determine c. X = 49 d. X = 47.5

Cannot determine

Which of the following actions will always change the value of the mean? a. Changing the value of one score b. Removing a score from the distribution c. Adding a new score to the distribution d. All 3 of the other choices are correct.

Changing the value of one score

In a negatively skewed distribution of exam scores, Tom scored at the mean, Mary scored at the median, and Jane scored at the mode. Who had the highest score? a. Cannot be determined from the information given b. Mary c. Tom d. Jane

Jane

To compute population variance, the sum of the squared deviations (SS) is divided by ____. a. N b. n - 1 c. N - 1 d. n

N

A sample of n = 40 scores has a mean of M = 75. If one new score with a value of X = 90 is added to the sample, what will happen to the sample mean? a. The mean will increase. b. The mean will decrease. c. Cannot be determined from the information provided d. The mean will remain the same.

The mean will increase

For the following sample, what would happen to the range is the score of X = 2 were changed to X = 9? Scores: 1, 1, 2, 5, 7, 10 a. The range would increase by 9 points. b. The range would decrease by 2 points. c. The range would increase by 7 points. d. The range would not be changed.

The range would not be changed.

A sample of n = 5 scores has a mean of M = 9. What is ∑X for this sample? a. 9/5 = 1.80 b. 5(9) = 45 c. Cannot be determined from the information given d. 5/9 = 0.555

The sample mean will increase.

A sample has a mean of M = 25. If a new score with a value of X = 25 is added to the sample, what effect will it have on the sample mean? a. Cannot be determined from the information given b. The sample mean will decrease. c. The sample mean will increase. d. The sample mean will remain the same.

The sample mean will remain the same

Which symbol is used to identify a single score? a. X b. ∑ c. n d. N

X

For a sample with M = 100 and s = 10, what is the score corresponding to z = 1.50? a. X = 115 b. X = 110.5 c. X = 101.5 d. X = 105

X = 115

A distribution with µ = 35 and σ = 8 is being standardized so that the new mean and standard deviation will be µ = 50 and σ = 10. When the distribution is standardized, what value will be obtained for a score of X = 39 from the original distribution? a. X = 55 b. X = 54 c. Impossible to determine without more information d. X = 1.10

X = 55

In a frequency distribution graph, frequencies are presented on the and the scores (categories) are listed on the ______. a. class interval/horizontal line b. Y axis/X axis c. horizontal line/vertical line d. X axis/Y axis

Y axis/X axis

For the past 20 years, the high temperature on April 15th has averaged µ = 62 degrees with a standard deviation of σ= 8. Last year, the high temperature was 66 degrees. Based on this information, last year's temperature on April 15th was _____. a. far above average b. a little above average c. above average, but it is impossible to describe how much above average d. There is not enough information to compare last year with the average.

a little above average

The normal distribution is an example of a. a smooth curve showing data from a population b. a histogram showing data from a sample c. a bar graph showing data from a population d. a polygon showing data from a sample

a smooth curve showing data from a population

A z-score of z = −2.00 indicates a position in a distribution that is below the mean by a distance equal to 2 standard deviations. What position is indicated by a z-score of z = +1.00? a. below the mean by 1 point b. above the mean by a distance equal to 1 standard deviation c. below the mean by a distance equal to 1 standard deviation d. above the mean by 1 point

above the mean by a distance equal to 1 standard deviation

What is the first step to be performed when computing ∑(X + 1)2? a. add 1 to each score b. square the (X + 1) values c. add the squared (X + 1) values d. square the sum of the (X + 1) values

add 1 to each score

Which of the following is a method for obtaining n for the scores in a frequency distribution table? a. multiply each X value by its f value and then add the resulting products b. add the values in the f column c. add the values in the X column d. multiply the sum of the X values by the sum of the f values

add the values in the f column

Which of the following is an example of a continuous variable? a. gender b. phone number c. age d. number brothers and sisters

age

For a sample of n = 10 scores, how many scores are used to compute the standard deviation? a. 2 b. all 10 c. 9 d. 3

all 10

What kind of graph is appropriate for scores measured on a nominal scale? a. either a histogram or a polygon b. polygon c. bar graph d. histogram

bar graph

In a population of N = 6, five of the individuals all have scores that are exactly 1 point above the mean. From this information you can determine that the score for the sixth individual must be _____. a. not enough information to describe the 6th score b. below the mean by 1 point c. below the mean by 5 points d. also above the mean by 1 point

below the mean by 5 points

What kind of variable consists of infinitely divisible categories? a. rational b. continuous c. irrational d. discrete

continuous

A researcher records the average temperature and the number of serious crimes each day for the month of June and finds a tendency for crime to increase as the temperature increases. What kind of research design was used for this study? a. noncorrelational b. nonexperimental c. experimental d. correlational

correlational

What kind of research study measures two different variables for each individual in one group of participants? a. experimental b. noncorrelational c. nonexperimental d. correlational

correlational

Organizing a set of scores in a graph would be an example of _____________. a. organizational statistics b. inferential statistics c. descriptive statistics d. parametric statistics

descriptive statistics

One sample of n = 4 scores has a mean of M = 10, and a second sample of n = 4 scores has a mean of M = 20. If the two samples are combined, then what value will be obtained for the mean of the combined sample? a. less than 15 but more than 10 b. equal to 15 c. None of the other choices is correct. d. greater than 15 but less than 20

equal to 15

For a perfectly symmetrical distribution with µ = 30, what is the value for the median? a. equal to 30 b. less than 30 c. cannot be determined from the information given d. greater than 30

equal to 30

Elliot and Niesta (2008) separated a group of men into two equivalent groups and asked each man to judge the attractiveness of a woman shown in a photograph. The researchers manipulated the background for the photograph so one group saw the picture on a white background and for the other group the background was red. The woman was rated significantly more attractive when the background was red. What kind of research design was used for this study? a. experimental b. correlational c. nonexperimental d. noncorrelational

experimental

Statistical techniques that use the limited information from samples to make general conclusions about populations are called ________ . a. descriptive statistics b. organizational statistics c. parametric statistics d. inferential statistics

inferential statistics

For a particular sample, the largest distance (deviation) between a score and the mean is 11 points. The smallest distance between a score and the mean is 4 points. Therefore, the standard deviation _____. a. It is impossible to say anything about the standard deviation. b. is probably between 4 and 11 c. is probably greater than 11 d. is probably less than 4

is probably between 4 and 11

A distribution can have more than one _____. a. None of the other choices is correct. b. mode c. mean d. median

mode

For any distribution, you can be sure that at least one individual has a score equal to the _____. a. mean b. All of the other 3 choices are correct. c. median d. mode

mode

The 721 students in the new freshman class have an average combined mathematics and verbal SAT score of 1220. If you selected a sample of 50 new freshmen and calculated their average combined score, what value would you obtain? a. near but probably not equal to 1220 b. greater than 1220 c. 1220 d. less than 1220

near but probably not equal to 1220

What shape would you expect for the distribution of scores from a very easy exam for a large class of students? a. symmetrical b. normal c. positively skewed d. negatively skewed

negatively skewed

Recording the gender of newborns at a county hospital is an example of using which scale of measurement? a. interval b. ratio c. nominal d. ordinal

nominal

Where are the scores with the highest frequencies located in a distribution with positive skew? a. on the left side of the distribution b. on the right side of the distribution c. at two distinct peaks d. in the middle of the distribution

on the left side of the distribution

Sorting watermelons into small, medium, and large sizes is an example of using which scale of measurement? a. ordinal b. interval c. nominal d. ratio

ordinal

What term is used to identify the entire group of individuals that a researcher would like to study? a. statistic b. parameter c. population d. sample

population

If a researcher is able to say that one score is twice a large as another, then what scale of measurement is being used? a. ordinal b. ratio c. interval d. nominal

ratio

The population standard deviation is identified by a lowercase Greek sigma (σ). What symbol is used to identify the standard deviation for a sample? a. s2 b. σ 2 c. σsample d. s

s

Although researchers are usually interested in very large groups, such as all of the adolescents in the United States, they typically select smaller groups to actually participate in their research studies. What are these smaller groups called? a. statistics b. populations c. samples d. parameters

samples

A distribution of N = 3 scores consists of 5, 7, and 50. What is the best way to present these data? a. use a regular frequency distribution table b. simply list the three scores c. sketch a histogram or polygon d. use a grouped frequency distribution table

simply list the three scores

The variability of the scores in a sample tends to be _______ the variability of the scores in the population from which the sample was obtained. a. exactly the same as b. smaller than c. larger than d. unrelated to

smaller than

Jones, Thomas, and Piper (2003) recruited students from bars and restaurants and asked them to rate the attractiveness of women shown in photographs and to describe their current state of intoxication. The study found that participants who were moderately intoxicated produced higher attractiveness ratings than those produced by sober participants. For this study, what kind of variable is the attractiveness rating that each participant gives to the photograph? a. the quasi-independent variable b. the independent variable c. the dependent variable d. the quasi-dependent variable

the dependent variable

In an experimental study, what name is given to the variable that differentiates the groups being compared? a. the independent variable b. the dependent variable c. the quasi-dependent variable d. the quasi-independent variable

the independent variable

What is the mean for the sample presented in the following frequency distribution table? X f 4 1 3 2 2 3 1 4 a. 2.0 b. 3.0 c. 3.5 d. 2.5

the mean

One item on a questionnaire asks students how many times in a typical week they eat at a fast-food restaurant. The response choices are (1) Never, (2) Once, (3) Twice, (4) Three or more times. What is the best measure of central tendency for the data from this question? a. the mode b. Central tendency cannot be determined for these data. c. the mean d. the median

the median

A professor records the academic major for each student in a class of n = 40. What would be the best measure of central tendency for these data? a. the mean b. Central tendency cannot be determined for these data. c. the mode d. the median

the mode

What determines the width of the bars in a histogram? a. the frequency of a score b. the apparent limits of a score or interval c. The bar width is arbitrary. d. the real limits of a score or class interval

the real limits of a score or class interval

A recent study had one group of students study text printed on paper and another group study the same text on a computer screen. Both groups were then given a test on the material to compare the effectiveness of the two study techniques. What is the dependent variable for this study? a. the group studying from a computer screen b. the scores on the test c. the group studying from paper d. paper versus computer

the scores on the test

he symbol SS stands for the ______. a. the sum of scores squared b. the sum of the deviations squared c. the sum of squared deviations d. the sum of squared scores

the sum of squared deviations

Under what circumstances would a score that is 15 points above the mean be considered an extreme score? a. when the population standard deviation is much smaller than 15 b. when the population standard deviation is much larger than 15 c. when the population mean is much larger than 15 d. when the population mean is much smaller than 15

when the population standard deviation is much smaller than 15

In a distribution with μ = 60 and σ = 10 a score of X = 80 corresponds to a z-score of z = +2.00 because it is above the mean by exactly 2 standard deviations. For this same distribution, what is the z-score corresponding to X = 65? a. z = −0.50 b. z = +1.00 c. z = +0.50 d. z = +0.25

z = +0.50

In a sample with M = 60 and s = 10 a score of X = 70 corresponds to a z-score of z = +1.00 because it is above the mean by exactly 1 standard deviation. For this same distribution, what is the z-score corresponding to X = 65? a. z = +0.50 b. z = +0.25 c. z = +1.00 d. z = −0.50

z = −0.50

A location that is above the mean by one half of a standard deviation is assigned a z-score of z = +0.50. What z-score is assigned to a location that is below the mean by one standard deviation? a. z = +2.00 b. z = +1.00 c. z = −2.00 d. z = −1.00

z = −1.00

In a sample with a mean of M = 45 and a standard deviation of s = 5, a z-score of z = −2 corresponds to X = 35 because the score is below the mean by exactly 2 standard deviations. What is the z-score corresponding to X = 40? a. z = −5.00 b. z = −0.50 c. z = +1.00 d. z = −1.00

z = −1.00

For a normal distribution, z = 1.28 separates the highest 10% of the distribution from the lowest 90%. What z-score separates the lowest 10% of the distribution from the rest? a. z = −0.90 b. z = −1.28 c. z = 1.28 d. z = 0.90

z = −1.28

A population with µ = 85 and σ = 12 is transformed into z-scores. After the transformation, the population of z-scores will have a mean of _____. a. Cannot be determined from the information given b. µ = 0 c. µ = 1.00 d. µ = 85

µ = 0

A population of scores has µ = 20 and σ = 5. If two points are added to every score in the population, then the new values for the mean and standard deviation would be _____. a. µ = 20 and σ = 7 b. µ = 22 and σ = 7 c. µ = 22 and σ = 5 d. µ = 20 and σ = 5

µ = 22 and σ = 5

A population of scores has µ = 20 and σ = 5. If every score in the population is multiplied by 2, then the new values for the mean and standard deviation would be _____. a. µ = 40 and σ = 5 b. µ = 20 and σ = 10 c. µ = 20 and σ = 5 d. µ = 40 and σ = 10

µ = 40 and σ = 10

If your exam score is X = 60, which set of parameters would give you the best grade? a. μ = 55 and σ = 5 b. μ = 55 and σ = 10 c. μ = 50 and σ = 5 d. μ = 50 and σ = 10

μ = 50 and σ = 5