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1 Name: Score: / Homework 3 Part 1 null 1 For the following sample of scores, the standard deviation is. Scores: 7, 2, 4, 6, 4, 7, 3, 7 Answer Key: 2 2 For any set of data, the sum of the deviation scores will always be. A. impossible to determine without more information B. equal to zero C. greater than zero D. less than zero 3 For the following set of scores, the (x 2 ) is. Scores: 10, 10, 8, 3, 6, 5, 2, 7, 3 Answer Key: 396

2 4 A student kept track of the number of hours she studied each day for a 2-week period. The following daily scores were recorded (scores are in hours): 2.5, 3.2, 3.8, 1.3, 1.4, 0, 0, 2.6, 5.2, 4.8, 0, 4.6, 2.8, 3.3. The mean for this set of scores is. (Make sure that you round to two decimal places.) Answer Key: For a normally distributed set of data, what percentage of these data lie within three standard deviations of the mean? A. 99.7% B. 68% C. 95% D % Answer Key: A 6 For the following population of scores, the variance is. Scores: 1, 9, 8, 5, 7 Answer Key: 8

3 7 The value for the interquartile range is determined by. A. the middle scores in the distribution B. all of the scores in the distribution C. the extreme scores (both high and low) in the distribution D. the extremely high scores in the distribution Answer Key: A 8 For the following distribution, state whether you would use the mean or the median to represent the central tendency of the distribution. Scores: 2, 3, 8, 5, 7, 8 A. Median B. Mean 9 The value of one score in a distribution is changed from x = 20 to x = 30. Which measure(s) of central tendency is (are) certain to be changed? A. the mean and the median B. the mode C. the mean D. the median Answer Key: C

4 10 For the following frequency distribution table, the mean of x is. x f Answer Key: A population of scores has = 50 and = 10. If every score in the population is multiplied by 2, then the new mean and standard deviation would be. A. = 50 and = 10 B. = 50 and = 20 C. = 100 and = 20 D. = 100 and = 10 Answer Key: C 12 For the following set of scores, the (x) 2 is. Scores: 10, 10, 8, 3, 6, 5, 2, 7, 3 Answer Key: 2916

5 13 Attachments histogram.pdf For the set of scores in the frequency distribution histogram below, the mode is. Answer Key: 2 14 A population of N = 5 scores produces SS = 20. The variance for this population is. A. 5 B. 4 C. 5 D. 4 Answer Key: D 15 A sample consists of n = 16 scores. How many of the scores are used to calculate the sample variance? A. 15 B. all 16 C. 2 D. 8

6 16 Given the following values of central tendency for this distribution, determine whether the distribution is symmetrical, positively skewed, or negatively skewed: Mean = 14, median = 12, mode = 10 A. symmetrical B. negatively skewed C. positively skewed Answer Key: C 17 A population of scores has = 50 and = 10. If 5 points are added to every score in the population, then the new mean and standard deviation would be. A. = 55 and = 10 B. = 55 and = 15 C. = 50 and = 10 D. = 50 and = 15 Answer Key: A 18 What is the mean for the following sample of scores? Scores: 1, 2, 5, 4 A. 4 B. 12 C. 6 D. 3 Answer Key: D

7 19 For the following sample of scores, the variance is. Scores: 7, 2, 4, 6, 4, 7, 3, 7 Answer Key: 4 20 The mean is an appropriate measure of central tendency for summarizing data that that have been measured on a nominal scale. True False Answer Key: False 21 The sum of the squared deviation scores is SS = 60 for a sample of n = 5 scores. What is the variance for this sample? A. 12 B. 15 C. 240 D. 300

8 22 On an exam with a mean of = 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. = 10 B. = 5 C. = 1 D. cannot determine from the information given Answer Key: C 23 Which of the following symbols identifies the sample standard deviation? A. s 2 B. 2 C. D. s Answer Key: D 24 A population with a mean of = 6 has x = 42. How many scores are in the population? A. N = 7 B. N = 0.14 C. N = 252 D. cannot be determined from the information given Answer Key: A

9 25 For the following distribution, state whether you would use the mean or the median to represent the central tendency of the distribution. Scores: 1.2, 0.8, 1.1, 0.6, 25 A. mean B. median 26 Attachments histogram.pdf For the set of scores in the frequency distribution histogram below, the median is. Answer Key: The mean is a preferred measure for describing skewed distributions. True False Answer Key: False 28 For the following population of scores, the standard deviation is. Scores: 1, 9, 8, 5, 7. (Round your answer to two decimal places.) Answer Key:

10 29 Attachments histogram.pdf For the set of scores in the frequency distribution histogram below, the mean is. Answer Key: If a negatively skewed distribution has a mean of 50, then the mode is probably greater than 50. True False Answer Key: True 31 For a perfectly symmetrical distribution with µ = 30, the median would have a value. A. cannot be determined from the information given B. equal to 30 C. greater than 30 D. less than 30

11 32 A sample of n = 6 scores has a mean of M = 8. If one score with a value of x = 3 is removed from the sample, what is the mean for the remaining scores? A. 8 B. 5 C. 9.6 D. 9 Answer Key: D 33 A sample consists of n = 16 scores. How many of the scores are used to calculate the range? A. all 16 B. 4 C. 2 D. 8 Answer Key: C 34 Given the following values of central tendency for this distribution, determine whether the distribution is symmetrical, positively skewed, or negatively skewed: Mean = 14, median = 14, mode = 14 A. symmetrical B. negatively skewed C. positively skewed Answer Key: A

12 35 How would you characterize the shape of the frequency distribution histogram shown below? Attachments histogram.pdf A. symmetrical B. negatively skewed C. bimodal D. positively skewed Answer Key: D 36 A set of n = 6 scores has a mean of M = 10. Another set of scores has n = 4 and M = 20. If these two sets of scores are combined, what is the mean for the combined group? A. 16 B. 15 C. cannot be determine from the information given D. 14 Answer Key: D 37 A population has µ = 40 and = 8. If each score is divided by 2, the new standard deviation will be. A. 20 B. 4 C. 8 D. insufficient information, cannot be determined

13 38 What shape would you expect for the distribution of scores from a very hard exam for a large class of students? A. normal B. negatively skewed C. positively skewed D. symmetrical Answer Key: C

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