EXAM 1 Quizzes

A sample of n = 8 scores has a mean of M = 16. For this sample ΣX = 2.​ -True or False

False

For a negatively skewed distribution, the mean usually has a larger value than either the median or the mode.​ -True or False

False

For a population with µ = 70 and σ = 5, about 95% of the individuals will have scores between X = 65 and X = 75.​ -True or False

False

For the distribution in the following table, the 90th percentile is X = 27.5. ​ X c% 25-29 100% 20-24 80% 15-19 20% -True or False

False

It is possible to have a non-uniform distribution of scores where no individual has a score exactly equal to the mode.​ -True or False

False

In a correlational study, ____.​ a) ​one variable is measured and two groups are compared b) two variables are measured and there is only one group of participants c) one variable is measured and there is only one group of participants d) two variables are measured and two groups are compared

b) two variables are measured and there is only one group of participants

There are situations for which it is either impossible to compute a mean or the mean does not provide a central, representative value.​ -True or False

True

To calculate the variance for a population, SS is divided by N.​ -True or False

True

What is the value of SS (sum of squared deviations) for the following set of scores? Scores: 8, 3, 1​ a) ​26 b) ​29 c) ​74 d) ​144

a) 26

What is the final step to be performed when computing Σ(X - 2)2?​ a) Sum the squared values. b) ​Subtract 2 points from each score. c) ​Square each value. d) ​Subtract 22 from each X2 value.

a) Sum the squared values.

There is a six-point difference between two sample means. If the two samples have the same variance, then which of the following values for the variance would make the mean difference easiest to see in a graph showing the two distributions.​ a) s2 = 2 b) ​s2 = 8 c) ​s2 = 16 d) ​s2 = 64

a) s2 = 2

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

a) ​Y axis; X axis

You have a score of X = 75 on a statistics exam. The mean score for the class on the exam is μ = 70. Which of the following values for the standard deviation would give you the highest position within the class?​ a) ​σ = 1 b) ​σ = 5 c) ​σ = 10 d) ​σ = 12

a) ​σ = 1

For the following distribution of quiz scores, How many individuals had a score of X = 2?​ X f 5 6 4 5 3 5 2 3 1 2 ​ a) 1 b) ​3 c) ​2 d) ​5

b) 3

A sample of n = 15 scores ranges from a high of X = 11 to a low of X = 3. If these scores are placed in a frequency distribution table, how many X values will be listed in the first column of that table?​ a) ​11 b) ​9 c) ​8 d) ​15

b) 9

A researcher is measuring the amount of time needed to solve a set of anagrams for a sample of n = 15 students. However, one of the participants fails to solve the problems so the researcher has an undetermined score. What is the best measure of central tendency for these data?​ a)​ mean b) ​median c) ​mode d) ​weighted mean

b) median

A professor records the number of students who are absent each day for the semester. Because this is a numeric, discrete variable, a bar graph should be used to show the frequency distribution.​ -True -False

-False

For the following scores, Σ(X + 1)2 = 81. Scores: 1, 3, 0, 1​ -True -False

-False

For the following scores, Σ(X - 1) = 10. Scores: 1, 3, 7​ -True -False

-False

In a grouped frequency distribution table, the top value in each class interval should be a multiple of the interval width.​ -True -False

-False

In an experimental study, individuals in a control condition receive the experimental treatment.​ -True -False

-False

For the following scores, ΣX2 = 35. Scores: 1, 3, 5​ -True -False

-True

Students in an introductory art class are classified as art majors and non-art majors. This is an example of measurement on a nominal scale.​ -True -False

-True

The goal for an experiment is to demonstrate that changes in one variable are responsible for causing changes in a second variable.​ -True -False

-True

What is the value of Σ(X - 1)2 for the following scores?​ Scores: 1, 2, 1, 4 ​- 16 ​- 49 ​- 10 ​- 36

10

What is the mode for the population of scores shown in the frequency distribution table?​ X f 5 1 4 2 3 3 2 4 1 2 a) 2​ b) ​3 c) ​3.5 ​d) 4

2

For the following distribution, what is the width of each class interval?​ X f 20-24 2 15-19 5 10-14 4 5-9 1​ a) ​10 b) ​5 c) ​4.5 d) 4​

5

A sample of n = 5 scores has a mean of M = 12. What is ΣX for this sample?​ a) ​12/5 = 2.40 b) 5/12 = 0.417 c) ​5(12) = 60 d) ​52=25

5(12) = 60

What is the mean for the following scores? Scores: 1, 6, 14​ ​ a) 3 b) ​6 c) ​7 d) ​10.5

7

A distribution of scores has a mean of 50, a median of 53, and a mode of 56. Based on this information it appears that the distribution is negatively skewed.​ -True or False

True

A population of N = 5 scores has SS = 20 and σ2 = 4. If the 5 scores were a sample, the value of SS would still be 20 but the variance would be s2 = 5.​ -True or False

True

A population with SS = 90 and a variance of 9 has N = 10 scores.​ -True or False

True

A sample of n = 6 scores has ΣX = 48. This sample has a mean of M = 8.​ -True or False

True

A sample with a variance of 25 has a standard deviation equal to 5 points.​ -True or False

True

For the distribution in the following table, the percentile rank for X = 19.5 is 20%.​ X c% 25-29 100% 20-24 80% 15-19 20% -True or False

True

Which description provides an example of a continuous variable?​ a) ​The gender of each student in a psychology class b) ​The amount of time to solve a problem c) The number of males in each class offered by the college d) The number of children in a family

b) ​The amount of time to solve a problem

If the following continuous distribution was shown in a histogram, the bar above the 15-19 interval would reach from ____ to ____.​ X f 20-25 2 15-19 5 10-14 4 5-9 1 a) ​X = 15.5 to X = 19.5 b) ​X = 14.5 to X = 19.5 c) ​X = 15.0 to X = 19.0 d) X = 15.5 to X = 18.5​

b) ​X = 14.5 to X = 19.5

After measuring two individuals, a researcher can say that Tom's score is four points higher than Bill's. The measurements must come from a(n) ____ scale.​ a) ​nominal b) ​interval or ratio c) ​ordinal d) ​interval

b) ​interval or ratio

The normal distribution is ____.​ a) ​skewed to the right b) ​symmetric c) ​asymmetric d) ​skewed to the left

b) ​symmetric

Which set of scores has the smallest standard deviation?​ a) ​11, 17, 31, 53 b) ​5, 11, 42, 22 c) ​145, 143, 145, 147 d) ​27, 105, 10, 80

c) 145, 143, 145, 147

In a grouped frequency distribution one interval is listed as 50-59. Assuming that the scores are measuring a continuous variable, what are the real limits of this interval?​ a) ​50 and 59 b) 50.5 and 59.5 c) ​49.5 and 59.5 d) ​49.5 and 60.5

c) 49.5 and 59.5

If a variable can be divided into an infinite number of fractional parts, then it is a(n) ____ variable.​ a) discrete b) ​independent c) ​continuous d) ​dependent

c) ​continuous

A researcher uses an anonymous survey to investigate the study habits of American college students. Based on the set of 56 surveys that were completed and returned, the researcher finds that these students spend an average of 4.1 hours each week working on course material outside of class. For this study, the average of 4.1 hours is an example of a ____.​ a)​ sample b) ​population c) ​statistic d) ​parameter

c) ​statistic

For the following frequency distribution of exam scores, what is the lowest possible reported score on the exam?​ X f 90-94 3 85-89 4 80-84 5 75-79 2 70-74 1 a) x = 90 b) ​x= 94 c) ​x = 70 d) ​x = 74

c) ​x = 70

For a sample of n = 16 scores, how many scores are used to calculate the sample variance?​ a) ​2 b) ​8 c) ​15 d) ​16

d) 16

A researcher uses an anonymous survey to investigate the study habits of American college students. Based on the set of 56 surveys that were completed and returned, the researcher finds that these students spend an average of 4.1 hours each week working on course material outside of class. For this study, the set of 56 students who returned surveys is an example of a ____.​ a) parameter b) ​population c) ​statistic d) ​sample

d) sample

What term is used to describe the shape of a distribution in which the scores pile up on the left-hand side of the graph and taper off to the right?​ a) symmetrical b) ​negatively skewed c) ​normal d) ​positively skewed

d) ​positively skewed

A population of scores has µ = 50 and σ = 5. If every score in the population is multiplied by 3, then what are the new values for the mean and standard deviation?​ a) ​µ = 50 and σ = 5 b) ​µ = 50 and σ = 15 c) ​µ = 150 and σ = 5 d) ​µ = 150 and σ = 15

d) ​µ = 150 and σ = 15

You have a score of X = 65 on a math exam. The mean score for the class on the exam is μ = 70. Which of the following values for the standard deviation would give you the most favorable position within the class?​ a) ​σ = 0 b) ​σ = 1 c) ​σ = 5 d) ​σ = 10

d) ​σ = 10

You are instructed to subtract four points from each score and find the sum of the resulting values. How would this set of instructions be expressed in summation notation?​ -​ ΣX - 4 ​- Σ(4 - X) ​- Σ (X - 4) ​- 4 - ΣX

Σ (X - 4)