**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 |

30 |

- 20%, 33%, 50%, 67%, 100%
- 2, 0.13, 0.17, 0.33, 0.17
- 20%, 13%, 17%, 33%, 17%
- 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?**

- 20
- 49
- 00
- 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**

- Smaller
- larger
- the same
- 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**

- a sample of moviegoers who paid to see the movie in a theater
- a population of moviegoers who paid to see the movie in a theater
- an independent variable
- 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?**

- sampling with replacement
- sampling without replacement

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

- independent variable
- quasi-independent variable
- 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?**

- 1/6
- 3/6
- 1/9
- 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

- Researcher A
- Researcher B
- 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,**

- the degrees of freedom for sample variance decrease
- the value of sample variance decreases
- the value in the numerator for sample variance increases
- 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**

- 07
- 14
- 05
- 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

- Sample A
- Sample B
- Both samples have the same standard deviation.

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

- Gender
- ethnicity
- rankings
- brand name

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

- fall above the mean
- fall below the median
- fall above and below the mode
- 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?**

- No, because the z score indicates 0 improvement.
- No, because the z score is not negative (indicating a reduction in symptoms).
- Yes; in fact, she actually reduced the mean number of symptoms to 0.
- 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?**

- Nominal
- ordinal
- interval
- ratio

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

- True
- 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?
**

- 7
- 0
- 44
- 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?**

- bar chart
- pie chart
- histogram
- 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?**

- The interval width is too small.
- The interval width is unequal.
- The class intervals overlap.
- 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**

- ungrouped data
- grouped data
- inferential statistics
- population parameters

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

- True
- False

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

- µ; M
- M; µ
- n; N
- N; n

**Course**: PSY-380 Introduction to Probability and Statistics

**School**: Grand Canyon University

- 24/03/2018
- 5