midterm_sol

midterm_sol - Name:_ Statistics 528 Midterm Solutions...

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1 Name:__________________ Statistics 528 – Midterm Solutions Winter 2004 INSTRUCTIONS Show your work on all problems to receive full credit. Problem 1 (15 points) In a statistics class with 136 students, the professor recorded how much money each student had in his or her wallet during the first class of the quarter. The histogram below is of the data collected. 100 50 0 60 50 40 30 20 10 0 Amount of Money 10 20 30 40 60 Indicate whether each of the statements is true or false. If false, explain briefly why it is false . a) The percentage of students with under $10.00 in their possession is about 50%. True or False True b) The distribution is skewed to the right. True or False True c) A normal density curve is a good approximation to the histogram. True or False
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2 False, because the distribution is asymmetric (skewed to the right with outliers). d) The median would be a better measure than the mean in describing the center of the distribution. True or False True e) The median amount of money students have is over $20.00. True or False False, because the number of students with under $20.00 in their possession is over 100 (out of 136), thus the median can not be more than $20.00.
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3 Problem 2 (20 points) The following are types of plots that we have discussed in class. For TWO of the types of plots, describe i) how to make the plot and ii) the purpose of the plot (what do you hope to learn about the distribution of a variable or the relationship between two variables) using the plot. a) BOXPLOT A boxplot is constructed using the five-number-summary of the distribution of a variable (min., 1 st quartile, median, 3 rd quartile, max.). A central box is drawn extending from the 3 rd quartile of the distribution to the 1 st quartile of the distribution with a horizontal line at the median. Lines extending from the center box are drawn up to the maximum value and down to the minimum value of the variable. Boxplots are used to graphically summarize the distribution of a variable and are good for summarizing skewed distributions. Side-by-side boxplots are also convenient for comparing the distributions of multiple variables that have similar ranges. b) NORMAL QUANTILE PLOT
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This note was uploaded on 07/26/2011 for the course STA 528 taught by Professor Calder during the Winter '09 term at Ohio State.

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midterm_sol - Name:_ Statistics 528 Midterm Solutions...

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