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ID 1050 Practice Exam 3 Your name (print)________________________ Discrete Data The set of questions below all use the following set of data points taken from a discrete sample: 1, 2, 3, 4, 4, 4, 5, 5, 6, 6. 1) Make a bar graph of this data using the blank graph provided. 2) What is the mean of this distribution? a) 10 b) 4 c) 4.5 d) 9 5) What is the standard deviation of this sample data set? a) 1.63 b) 1.55 c) 4.00 d) 2.67 3) What is the median of this distribution? a) 10 b) 4 c) 4.5 d) 9 6) What is the variance of this distribution? a) 1.63 b) 1.55 c) 4.00 d) 2.67 4) What is the mode of this distribution? a) 10 b) 4 c) 4.5 d) 9 7) What is the skewness of this distribution? a) 1.22 b) 4.00 c) 1.41 d) 0.00 Definitions 8) A set of classes or groups based on name only, without a mathematical value or order (example: hair color): a) A nominal scale b) An ordinal scale c) An interval scale 10) A set of classes or groups based on their mathematical value relative to an absolute zero (example: height): a) A nominal scale b) An ordinal scale c) A ratio scale 9) A set of classes or groups based on relative rank only, without a mathematical value (example: relative dominance): a) A nominal scale b) An ordinal scale c) A ratio scale 11) The entire set of people or objects one wishes to characterize is called the _______. The subset that is actually measured is called the ________. a) Population; sample b) Sample; population R. Gist 1 of 4 Ver. D, Rev. 1 ID105 Exam 3 Continuous Data The set of questions below are all taken from the following set of data which comes from a sample which is continuously distributed: 1.1, 1.2, 1.3, 1.8, 2.4, 2.5, 3.7, 4.1, 4.8, 5.3 12) Draw a histogram of this data. Use the number of classes and the class width that is shown on the following blank graph: 13) What is the mean of this data? a) 2.82 b) 2.40 c) 1.50 d) 1.70 16) What is the standard deviation of this sample data set? a) 2.41 b) 1.50 c) 1.55 d) 4.56 14) What is the median of this data? a) 2.40 b) 2.45 c) 2.50 d) 2.82 17) What is the variance of this data? a) 2.41 b) 1.50 c) 1.55 d) 4.56 15) What is the mode of this data? a) 2.45 b) 2.40 c) 1.50 d) 1.70 18) What is the skewness of this data? a) 1.50 b) 4.50 c) 0.85 d) -1.75 More Definitions 19) When you look at the graph of a set of data and notice that there is a pronounced tail going off to the left, you can be pretty convinced that the data has ________. a) Negative skewness b) Positive skewness c) No skewness 22) Variables that can take on any real number value (integer or decimal) are: a) Discrete variables b) Skewed variables c) Continuous variables d) Standard variables 20) The measures of central tendency are: a) The mean b) The mode c) The median d) All of the above R. Gist 21) The measures of the spread or precision of the data are: a) The standard deviation and the variance b) The mean and the variance c) The skewness and the variance d) The mean and the skewness 2 of 4 Ver. D, Rev. 1 ID105 Exam 3 The Normal Curve The set of questions below are based on the following normal curve. This particular curve represents the scores of a large population on a standard SAT exam. The mean is 500 (=500) and the standard deviation is 100 (=100). The percentages given below represent the percentage of the population between the values on the horizontal axis. 23) On the standard SAT exam, Debbie scores 600. What percentage of all people taking this test will score higher than Debbie? a) 0.5% b) 2.5% c) 16% d) 84% 26) What is the highest grade someone else could have and still be in the lowest 16% of everyone taking the test? a) 300 b) 400 c) 500 d) 600 24) Using Debbie as an example, you can say that her grade lies at the ______ percentile. a) 0.5 th b) 2.5 th c) 16 th d) 84 th 27) What percentage of all people taking the exam scored at least a 300? a) 2.5% b) 16% c) 84% d) 97.5% 25) What is the lowest grade someone else could have and still be in the top 84% of all people taking the test? a) 300 b) 400 c) 500 d) 600 28) What percentage of all people taking the exam scored between 400 and 600? a) 34% b) 68% c) 16% d) 2.5% R. Gist 3 of 4 Ver. D, Rev. 1 ID105 Exam 3 The Standard Normal Curve The next set of questions is based on the standard normal curve. Use the z-score table at the bottom of this page to answer the following questions. 29) What area is under the curve to the right of a z-score of 0.8? a) 0.212 b) 0.455 c) 0.500 d) 0.882 30) What area is under the curve to the right of a negative z-score of z= -1.0? a) 0.104 b) 0.308 c) 0.500 d) 0.841 The next set of questions is based on normally distributed data representing the age of a certain population of 1000 individuals. The data has an average of 50 (=50) and a standard deviation of 10 (=10). [Recall that z=(x-)/] Using the z-score table at the bottom of this page, answer the following: 31) What percentage of the population is above an age of 50? a) 20 % b) 50 % c) 70 % d) 99.5% 32) What percentage of the population is between 35 and 65 years old? a) 6.7 % b) 30.8 % c) 68.0 % d) 86.6 % 33) How many in the population are between 35 and 65 years old? a) About 110 individuals b) About 278 individuals c) About 505 individuals d) About 866 individuals ____________________________________________________________________________ Z-Score Table (A) z-score 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 R. Gist (B) Area between z and the mean 0.000 0.040 0.079 0.118 0.155 0.192 0.226 0.258 0.288 0.316 0.341 0.364 0.385 0.403 0.419 0.433 (C) Area beyond z 0.500 0.460 0.421 0.382 0.345 0.309 0.274 0.242 0.212 0.184 0.159 0.136 0.115 0.097 0.081 0.067 (A) z-score 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 4 of 4 (B) Area between z and the mean 0.445 0.455 0.464 0.471 0.477 0.482 0.486 0.489 0.492 0.494 0.495 0.496 0.497 0.498 0.499 (C) Area beyond z 0.055 0.045 0.036 0.029 0.023 0.018 0.014 0.011 0.008 0.006 0.005 0.004 0.003 0.002 0.001 Ver. D, Rev. 1