Chapter 2: Problem 32
Briefly explain the concept of cumulative frequency distribution. How are the cumulative relative frequencies and cumulative percentages calculated?
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Chapter 2: Problem 32
Briefly explain the concept of cumulative frequency distribution. How are the cumulative relative frequencies and cumulative percentages calculated?
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The following data give the numbers of orders received for a sample of 30 hours at the Timesaver Mail Order Company. \(\begin{array}{llllllllll}34 & 44 & 31 & 52 & 41 & 47 & 38 & 35 & 32 & 39 \\\ 28 & 24 & 46 & 41 & 49 & 53 & 57 & 33 & 27 & 37 \\ 30 & 27 & 45 & 38 & 34 & 46 & 36 & 30 & 47 & 50\end{array}\) a. Construct a frequency distribution table. Take 23 as the lower limit of the first class and 7 as the width of each class. b. Calculate the relative frequencies and percentages for all classes. c. For what percentage of the hours in this sample was the number of orders more than 36 ?
The National Highway Traffic Safety Administration collects information on fatal accidents that occur on roads in the United States. Following are the number of fatal motorcycle accidents that occurred in each of South Carolina's 46 counties during the year 2009 (http://www-fars.nhtsa.dot.gov). \(\begin{array}{rrrrrrrrrrr}3 & 28 & 3 & 35 & 3 & 7 & 13 & 38 & 6 & 44 & 11 & 14 \\ 12 & 18 & 17 & 17 & 6 & 20 & 3 & 7 & 29 & 17 & 51 & 12 \\ 5 & 60 & 12 & 18 & 17 & 21 & 14 & 34 & 3 & 12 & 8 & 5 \\ 11 & 29 & 20 & 40 & 3 & 30 & 23 & 5 & 10 & 23 & & \end{array}\) a. Construct a frequency distribution table using the classes \(1-10,11-20,21-30,31-40,41-50\), and \(51-60\) b. Calculate the relative frequency and percentage for each class. c. Construct a histogram and a polygon for the relative frequency distribution of part b. d. What percentage of the counties had between 21 and 40 fatal motorcycle accidents during \(2009 ?\)
Each state collects information on every birth that occurs within its borders. The following data give the 2008 birth rates (number of births per 1000 people) for all of the 56 counties in the state of Montana (http://www.dphhs.mt.gov/statisticalinformation/vitalstats/index.shtml). \(\begin{array}{rrrrrrrr}10.1 & 22.2 & 15.8 & 12.2 & 7.7 & 3.1 & 14.5 & 7.8 \\\ 13.6 & 8.8 & 10.9 & 8.9 & 14.7 & 9.6 & 14.2 & 14.9 \\ 18.3 & 22.8 & 5.4 & 5.6 & 19.6 & 8.2 & 9.9 & 14.7 \\ 13.7 & 10.3 & 9.7 & 9.8 & 8.6 & 9.4 & 14.1 & 12.3 \\ 10.5 & 11.4 & 2.2 & 9.8 & 10.9 & 4.6 & 6.6 & 8.5 \\ 10.2 & 14.4 & 20.4 & 18.5 & 10.8 & 6.5 & 11.6 & 12.1 \\ 10.5 & 9.3 & 8.1 & 7.4 & 10.2 & 9.7 & 5.6 & 14.5\end{array}\) a. Construct a frequency distribution table using the classes 2 to less than 5,5 to less than 8,8 to less than 11,11 to less than 14,14 to less than 17,17 to less than 20 , and 20 to less than 23 . b. Calculate the relative frequency and percentage for each class. c. Construct a histogram and a polygon for the birth-rate percentage distribution. d. What percentage of the counties had a birth rate of less than 11 births per 1000 people?
What is a stacked dotplot, and how is it used? Explain.
Statisticians often need to know the shape of a population to make inferences. Suppose that you are asked to specify the shape of the population of weights of all college students. a. Sketch a graph of what you think the weights of all college students would look like. b. The following data give the weights (in pounds) of a random sample of 44 college students (F and M indicate female and male, respectively). \(\begin{array}{llllllll}123 \mathrm{~F} & 195 \mathrm{M} & 138 \mathrm{M} & 115 \mathrm{~F} & 179 \mathrm{M} & 119 \mathrm{~F} & 148 \mathrm{~F} & 147 \mathrm{~F} \\ 180 \mathrm{M} & 146 \mathrm{~F} & 179 \mathrm{M} & 189 \mathrm{M} & 175 \mathrm{M} & 108 \mathrm{~F} & 193 \mathrm{M} & 114 \mathrm{~F} \\ 179 \mathrm{M} & 147 \mathrm{M} & 108 \mathrm{~F} & 128 \mathrm{~F} & 164 \mathrm{~F} & 174 \mathrm{M} & 128 \mathrm{~F} & 159 \mathrm{M} \\ 193 \mathrm{M} & 204 \mathrm{M} & 125 \mathrm{~F} & 133 \mathrm{~F} & 115 \mathrm{~F} & 168 \mathrm{M} & 123 \mathrm{~F} & 183 \mathrm{M} \\ 116 \mathrm{~F} & 182 \mathrm{M} & 174 \mathrm{M} & 102 \mathrm{~F} & 123 \mathrm{~F} & 99 \mathrm{~F} & 161 \mathrm{M} & 162 \mathrm{M} \\ 155 \mathrm{~F} & 202 \mathrm{M} & 110 \mathrm{~F} & 132 \mathrm{M} & & & & \end{array}\) i. Construct a stem-and-leaf display for these data. ii. Can you explain why these data appear the way they do? c. Construct a back-to-back stem-and-leaf display for the data on weights, placing the weights of the female students to the left of the stems and those of the male students to the right of the stems. (See Exercise \(2.89\) for an example of a back-to-back stem-and-leaf plot.) Does one gender tend to have higher weights than the other? Explain how you know this from the display.
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