PSY-380 Week 3 Exam 1 Introduction to Probability and Statistics (Multiple Choice Questions)

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Description: This exam covers Chapters 1-7. Please review your work and Chapter readings to study for this exam.

1. The following is a simple frequency distribution table. If we convert this frequency distribution to relative percentages, which of the following gives the corresponding percentages in each interval listed from the top down?

Intervals    Frequency
44-46 6
41-43 4
38-40 5
35-37 10
32-34 5
  1. 20%, 33%, 50%, 67%, 100%
  2. 2, 0.13, 0.17, 0.33, 0.17
  3. 20%, 13%, 17%, 33%, 17%
  4. 6, 10, 15, 25, 30

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2. Below is the probability distribution for random variable x. What is the standard deviation of this probability distribution?

  1. 20
  2. 49
  3. 00
  4. 35

3. The distribution of personal income for U.S. citizens is positively skewed. If the median annual income is $44,000, this implies that the mean annual income is

  1. Smaller
  2. larger
  3. the same
  4. There is not enough information to answer this question.

4. Suppose that a researcher is interested in a group of 10 million people who paid to see a movie playing in theaters. In this example, the 10 million moviegoers would be regarded as

  1. a sample of moviegoers who paid to see the movie in a theater
  2. a population of moviegoers who paid to see the movie in a theater
  3. an independent variable
  4. a dependent variable

5. A researcher selects from a participant pool of 4 males and 6 females. He determines that the probability of selecting 2 male participants is p = 0.16. Based on this probability, what strategy did the researcher use to sample participants?

  1. sampling with replacement
  2. sampling without replacement

6. ________ is the variable in an experiment that is manipulated between conditions being observed.

  1. independent variable
  2. quasi-independent variable
  3. dependent variable

7. A gambler rolls a 3 with one roll of a single fair die. Given that the die was six-sided, what was the probability of rolling a 3 with one roll?

  1. 1/6
  2. 3/6
  3. 1/9
  4. 3/9

8. The following samples were selected by two researchers. Which is associated with a smaller standard error of the mean?

Researcher A: n = 25, μ = 5, σ = 7
Researcher B: n = 25, μ = 32, σ = 7

  1. Researcher A
  2. Researcher B
  3. They both have the same standard error.

9. All other things being equal (so assuming that the value of SS never changes), as sample size increases,

  1. the degrees of freedom for sample variance decrease
  2. the value of sample variance decreases
  3. the value in the numerator for sample variance increases
  4. the value in the denominator for sample variance decreases

10. The probability that a parent rewards a child with a dessert for eating a healthy meal is 0.07. Assuming independent outcomes, the probability that two parents reward their child’s healthy eating equals

  1. 07
  2. 14
  3. 05
  4. 005

11. A researcher records the following motor assessment scores for two samples of athletes. Which sample has the largest standard deviation?

Sample A: 8, 10, 12, 15, and 18
Sample B: 16, 18, 20, 23, and 26

  1. Sample A
  2. Sample B
  3. Both samples have the same standard deviation.

12. The median would be used to describe which of the following variables?

  1. Gender
  2. ethnicity
  3. rankings
  4. brand name

13. In a normal distribution, 50% of all data:

  1. fall above the mean
  2. fall below the median
  3. fall above and below the mode
  4. all of the above

14. A therapist has a goal to reduce the mean number of patient symptoms expressed for a particular disorder to two symptoms per day. Following therapy, she determines that the z score for 2 symptoms per day is 0. Assuming the data are normally distributed, did she reach her goal?

  1. No, because the z score indicates 0 improvement.
  2. No, because the z score is not negative (indicating a reduction in symptoms).
  3. Yes; in fact, she actually reduced the mean number of symptoms to 0.
  4. Yes, because a z score of 0 is the average, or mean.

15. A movie critic rates a movie on a scale from one (lowest) to four (highest) stars. What scale of measurement are the ratings?

  1. Nominal
  2. ordinal
  3. interval
  4. ratio

16. A sample mean is not always equal to a population mean.

  1. True
  2. False

17. A researcher computes the definitional formula for SS, and finds that Σ(x − M) = 44. If this is a sample of 12 scores, then what would the value of sample variance be using the computational formula?

  1. 7
  2. 0
  3. 44
  4. not possible to know because the scores are not given

18. Which of the following is a type of graphical display used to summarize qualitative, discrete data?

  1. bar chart
  2. pie chart
  3. histogram
  4. both a bar chart and a pie chart

19. A researcher distributes frequencies into the following intervals: 1-10, 11-20, 21-30, 31-40, 41-50, and 51 and above. What is wrong with this frequency distribution?

  1. The interval width is too small.
  2. The interval width is unequal.
  3. The class intervals overlap.
  4. One interval is an open class.

20. A researcher summarizes a set of frequency data into five intervals. This is an example of a frequency distribution for

  1. ungrouped data
  2. grouped data
  3. inferential statistics
  4. population parameters

21. The mean, median, and mode are all located at the 50th percentile in a perfect normal distribution.

  1. True
  2. False

22. The population mean is symbolized as ________, whereas the sample mean is symbolized as ________.

  1. µ; M
  2. M; µ
  3. n; N
  4. N; n

Course: PSY-380 Introduction to Probability and Statistics
School: Grand Canyon University

  • 24/03/2018
  • 5
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