PSY 211 Exam 1

A vertical line drawn through a normal distribution at z= 0.50 separates the distribution into two sections. What proportion of the scores are less that z=0.50? a)0.6915 b) 0.3085 c) 0.1915 d) 0.8830

a) 0.6915

What is the variance for the following population of scores? Scores: 5, 0, 3, 4 a) 3.5 b) 0 c) 1.87 d)4.67

a) 3.5

After recording the final letter grade (A,B,C,D,E) for each individual in a class of n=25 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

Which types of graphs are used for data from an interval scale? a) Histograms and polygons b) Polygons and bar graphs c) Histograms and bar graphs d) Histograms, bar graphs, and polygons

a) Histograms and polygons

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

a) Subtract 3 points from X=3

A researcher conducts an experiment to determine the effects that weak, moderate, or string doses of St. John's Wort has on memory for college students. What is the independent variable? a) The amount of St. John's Wort given to each participant b) The memory score for each participant c) the group of college students d) The weak dose of St. John's Wort

a) The amount of St. John's Wort given to each participant

On an exam with a mean of μ =70, you have a score of X=75. Which of the following values for the standard deviation would give you the highest position in the class? a) σ=1 b) σ=5 c) σ= 10 d) Cannot be determined from the information given

a) σ= 1

For a population with μ= 80 and σ= 6, what is the z-score corresponding with X=68? a) -0.50 b) -2.00 c) +2.00 d) -12.00

b) -2.00

What proportion of a normal distribution is located between z= +0.50 and z= +1.50? a) 0.9332 b) 0.2417 c) 0.4332 d) 0.6247

b) 0.2417

John drives to work each morning, and the trip takes an average of μ=38 minutes. The distribution of driving times is approximately normal with a standard deviation of σ= 5 minutes. For a randomly selected morning, what is the probability that John's drive to work will take less that 36 minutes? a) 0.6554 b) 0.3446 c) 0.1554 d) 0.2743

b) 0.3446

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

b) 16

For the following distribution, what percentage of the individuals have scores of X=3? X f 5 2 4 8 3 5 2 3 1 2 a) 2% b) 25% c) 10% d) 20%

b) 25%

A doctor is measuring children's height in inches, rounded to a whole. She obtains scores such as 40, 41, 42, 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

b) 41.5 and 42.5

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 consultant provides a ranking of the top 5 most important issues for a business. The ranking of issues represents a(n) ________ scale. a) Nominal b) Ordinal c) Interval d) Ratio

b) Ordinal

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

Under what circumstances is the median likely to produce a better measure of central tendency that the mean? a) With a symmetrical distribution of scores grin an interval or ratio scale b) With an extremely skewed distribution c) When the data consists of nominal measurements d) When the data are numerical scores from and interval or ratio scale

b) With an extremely skewed distribution

For the following frequency distribution of quiz scores, how many individuals took the quiz? X f 5 6 4 4 3 5 2 3 1 2 a) n=5 b) n=20 c) n=15 d) n=69

b) n=20

A researcher records the change in weight (gain or lost) for each individual in a sample of 25 freshman during the first semester of college. When he calculates the average change in weight, this average is an example of a _________. a) parameter b) statistic c) variable d) constant

b) statistic

Which of the following z-score values represents the location that is farthest away from the mean? a) z= +0.50 b) z= -2.00 c) z= -1.00 d) z= +1.00

b) z= -2.00

For a population with a standard deviation of σ=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

A populations with μ=45 and σ=5 is transformed into z-scores. After the transformation, what is the standard deviation for z-scores? a) σ= 5 b) σ= 1.00 c) σ= 0 d) cannot be determined from the information given

b) σ= 1.00

A normal distribution has a mean of μ=70 with σ=10. If one score is randomly selected from this distribution, what is the probability that the score will be greater that X=82? a) 0.7698 b) 0.3849 c) 0.1151 d) 0.8849

c) 0.1151

What proportion of a normal distribution is located between the mean and z= 1.40? a) 0.9192 b) 0.0808 c) 0.4192 d) 0.8384

c) 0.4192

A population has a mean of μ=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

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

For the following distribution of quiz scores, 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) 10 c) 5 d) 3

c) 5

For the following distribution, how many people have scores greater that X=14 X f 20-24 2 15-19 5 10-14 4 5-9 1 a) 2 b) 5 c) 7 d) 11

c) 7

What is the median for the following set of scores? Scores: 1, 2, 6, 11, 13, 17 a) 8.33 b) 6 c) 8.5 d) 11

c) 8.5

A researcher measures eye color (blue, brown, green, etc.) for a sample of n=50 people. Which measures 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

Which of the following is an example of a continuous variable? a) The type of color worn on a uniform b) The gender of each student in a psychology class c) The amount of time it takes to solve a problem d) The type of TV shows typically watched by college freshman

c) The amount of time it takes to solve a problem

Last week Sarah had exams in math and in spanish. On the math exam, the mean was μ=30 with σ=5, and Sarah had a score of X=40. On the spanish exam, the mean was μ=60 with σ=4, 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.

c) The grades are the same because the two exam scores are in the same location

If sample variance is computed by dividing SS by n-1, the the averaging sample variances across all possible random samples will gave a value that is _______ the population variance. a) smaller than b) larger than c) exactly equal to d) unrelated to

c) exactly equal to

A set of 10 scores has SS=90. If the scores are a sample, the sample variance is ____, and if the sores are a population, the population variance is _____. a) s2=9; σ2=9 b) s2=9; σ2=10 c) s2= 10; σ2=9 d)s2=10; σ2=10

c) s2=10; σ2=9

A class consists of 13 males and 25 females. If one student is randomly selected from the class, what is the probability of selecting a male? a) 13/25 b) 1/38 c) 13/36 d) 13/38

d) 13/38

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

d) 145, 143, 145, 147

In a correlational study, a) 1 variable is measured and 2 groups are compared b) 2 variables are measures and 2 groups are compared c) 1 variable is measures and there is only 1 group of participants d) 2 variables are measured and there is only 1 group of participants

d) 2 variables are measured and there is only one group of participants

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

d) 5

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

d) 52

What is the mode(s) for the population if scores shown in the frequency distribution table? X f 5 1 4 4 3 3 2 4 1 2 a) 2 b) 4 c) 3 d) Both A and B

d) Both A and B

Using sample data to draw conclusions about a population is an example of using__________. a) parameters b) statistics c) descriptive statistics d) inferential statistics

d) inferential statistics

A population has μ= 50 and σ=5. If every score is multiplied by 2, what are the new values for the mean and standard deviation? a) μ=50 and σ=5 b) μ=50 and σ=10 c) μ=100 and σ=5 d) μ= 100 and σ=10

d) μ= 100 and σ=10