Psychology Stats Exam 1

After recording the final grade (A, B, C, D, E) for each individual in a class of n = 26 students, the professor would like to display the grade distribution in a frequency distribution graph. What kind of graph should be used? a. A bar graph b. A histogram c. A polygon d. Either a histogram or a polygon

a. A bar graph

Last week, Sarah had exams in math and in Spanish. On the math exam, the mean was u = 30 with o = 5, and Sarah had a score of X = 45. On the Spanish exam, the mean was u = 60 with o = 8, and Sarah had a score of X = 68. For which class should Sara expect the better grade? a. Math b. Spanish c. The grades are the same because the two exam scores are in the same location. d. There is not enough information to determine which is the better grade.

a. Math

Students in an introductory art class are classified as art majors and non-art majors. What scale of measurement is being used to classify the students? a. Nominal b. Ordinal c. Interval d. Ratio

a. Nominal

For the following scores, which of the following actions will increase the range? Scores: 3, 7, 10, 15 a. Subtract 3 points from the score X = 3 b. Subtract 3 points from the score X = 7 c. Subtract 3 points from the score X = 10 d. Subtract 3 points from the score X = 15

a. Subtract 3 points from the score X = 3

A researcher conducts an experiment to determine whether moderate doses of St. Johns Wort have any effect on memory for college students. For this study, what is the independent variable? a. The amount of St. Johns Wort given to each participant b. The memory score for each participant c. The group of college students d. Cannot answer without more information

a. The amount of St. Johns Wort given to each participant

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

a. o = 1

What is the median for the following set of scores? Scores: 17, 1, 2, 6, 11 a. 4 b. 6 c. 8.5 d. 8

b. 6

Which of the following statements cannot be true for a distribution of scores? a. 60% of the scores are above the mean. b. 60% of the scores are above the median. c. 60% of the scores are above the mode. d. All of the other options are false statements.

b. 60% of the scores are above the median.

What score (X) in a distribution corresponds to a z-score of z = -1.00? a. It is below the mean by 1 point b. It is below the mean by a distance equal to 1 standard deviation c. It is above the mean by 1 point d. It is above the mean by a distance equal to 1 standard deviation

b. It is below the mean by a distance equal to 1 standard deviation

A frequency distribution of scores has a mean of µ = 29, a median of 24, and a mode of 20. What is the most likely shape for the population distribution? a. Symmetrical b. Positively skewed c. Negatively skewed d. Cannot be determined from the information given

b. Positively skewed

Which of the following is an example of a discrete variable? a. The age of each student in a psychology class b. The gender of each student in a psychology class c. The amount of time to solve a problem d. The amount of weight gained for each freshman at a local college

b. The gender of each student in a psychology class

A distribution with µ = 35 and o = 8 is being standardized so that the new mean and standard deviation will be µ = 50 and o = 10. In the old distribution, your score was X = 31. What is your score in the new distribution? a. X = 42 b. X = 45 c. X = 40 d. X = 31

b. X = 45

A population with u = 85 and o = 12 is transformed into z-scores. After the transformation, what is the standard deviation for the population of z-scores? a. o = 12 b. o = 1.00 c. o = 0 d. Cannot be determined from the information given

b. o = 1.00

For a population with a standard deviation of o = 6, what is the z-score corresponding to a score that is 12 points above the mean? a. z = 1 b. z = 2 c. z = 6 d. z = 12

b. z = 2

What is the variance for the following population of scores? Scores: 5, 2, 5, 4 a. 6 b. 2 c. 1.5 d. 1.22

c. 1.5

For the following distribution, what percentage of the individuals have scores of X = 1? X f 5 2 4 8 3 5 2 3 1 2 a. 2% b. 5% c. 10% d. 20%

c. 10%

Which set of scores has the smallest variability? 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

A population has a mean of = 30. If 3 points are added to each score, what is the mean for the new distribution? a. 27 b. 30 c. 33 d. Cannot be determined from the information given

c. 33

A doctor is measuring children's heights rounded to the nearest 1/2 inch. He obtains scores such as 40.0, 40.5, 41.0, and so on. What are the real limits for a score of X = 42? a. 41 and 43 b. 41.5 and 42.5 c. 41.75 and 42.25 d. 41.25 and 42.75

c. 41.75 and 42.25

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 for 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

A population of n = 8 scores has SUMX = 40. What is the population mean? a. 320 b. 20 c. 5 d. 0.2

c. 5

For the following distribution of quiz scores, if a score of X = 3 or higher is needed for a passing grade, how many individuals failed the quiz? X f 5 6 4 5 3 5 2 3 1 2 a. 2 b. 3 c. 5 d. 10

c. 5

For a population with u = 40 and o = 8, what is the X value corresponding to z = 1.50? a. 44 b. 50 c. 52 d. 58

c. 52

A researcher measures eye color (blue, brown, green, etc.) for a sample of n = 50 people. Which measure of central tendency would be appropriate to summarize the eye color variable? a. Mean b. Median c. Mode d. Any of the three measures could be used

c. Mode

The students in a psychology class seemed to think that the midterm exam was very easy. If they are correct, what is the most likely shape for the distribution of exam scores? a. Symmetrical b. Positively skewed c. Negatively skewed d. Normal

c. Negatively skewed

Organizing a set of scores in a table is an example of using _______. a. parameters b. statistics c. descriptive statistics d. inferential statistics

c. descriptive statistics

A set of 10 scores has SS = 90. If the scores are a sample, the sample variance is ____, and if the scores are a population, the population variance is ____. a. s2 = 9; o2 = 9 b. s2 = 9; o2 = 10 c. s2 = 10; o2 = 9 d. s2 = 10; o2 = 10

c. s2 = 10; o2 = 9

A population has u = 50 and o = 5. If 10 points are added to every score in the population, what are the new values for the mean and standard deviation? a. u = 50 and o = 5 b. u = 50 and o = 15 c. u = 60 and o = 5 d. u = 60 and o = 15

c. u = 60 and o = 5

A population of N = 100 scores has u = 30 and o = 4. What is the population variance? a. 2 b. 4 c. 8 d. 16

d. 16