Chapter 3: Problem 87
Construct two sets of numbers with at least five numbers in each set with the following characteristics: The means are different, but the standard deviations are the same. Report the standard deviation and both means.
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Chapter 3: Problem 87
Construct two sets of numbers with at least five numbers in each set with the following characteristics: The means are different, but the standard deviations are the same. Report the standard deviation and both means.
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Surfing College students and surfers Rex Robinson and Sandy Hudson collected data on the self-reported numbers of days surfed in a month for 30 longboard surfers and 30 shortboard surfers. $$ \begin{gathered} \text { Longboard: } 4,9,8,4,8,8,7,9,6,7,10,12,12,10,14,12, \\ 15,13,10,11,19,19,14,11,16,19,20,22,20,22 \\ \text { Shortboard: } 6,4,4,6,8,8,7,9,4,7,8,5,9,8,4,15,12,10, \\ 11,12,12,11,14,10,11,13,15,10,20,20 \end{gathered} $$ a. Compare the means in a sentence or two. b. Compare the standard deviations in a sentence or two.
Data on residential energy consumption per capita (measured in million BTU) had a mean of \(70.8\) and a standard deviation of \(7.3\) for the states east of the Mississippi River. Assume that the distribution of residential energy use if approximately unimodal and symmetric. a. Between which two values would you expect to find about \(68 \%\) of the per capita energy consumption rates? b. Between which two values would you expect to find about \(95 \%\) of the per capita energy consumption rates? c. If an eastern state had a per capita residential energy consumption rate of 54 million BTU, would you consider this unusual? Explain. d. Indiana had a per capita residential energy consumption rate of \(80.5\) million BTU. Would you consider this unusually high? Explain.
In 2017 a pollution index was calculated for a sample of cities in the eastern states using data on air and water pollution. Assume the distribution of pollution indices is unimodal and symmetric. The mean of the distribution was \(35.9\) points with a standard deviation of \(11.6\) points. (Source: numbeo. com) see Guidance page \(142 .\) a. What percentage of eastern cities would you expect to have a pollution index between \(12.7\) and \(59.1\) points? b. What percentage of eastern cities would you expect to have a pollution index between \(24.3\) and \(47.5\) points? c. The pollution index for New York, in 2017 was \(58.7\) points. Based on this distribution, was this unusually high? Explain.
The following dotplot shows the distribution of passing rates for the bar exam law schools in the United States in. The five number summary is $$ 0.60,0.84,0.90,0.94,1.00 $$ Draw the boxplot and explain how you determined where the whiskers go.
Data at this text's website show the gas taxes for each of the 50 states and the District of Columbia. A summary of the data is shown in the following table. Should the maximum and minimum values of this data set be considered potential outliers? Why or why not? You can check your answer by using technology to make a boxplot using fences to identify potential outliers. (Source: 2017 World Almanac and Book of Facts) $$ \begin{aligned} &\text { Summary statistics }\\\ &\begin{array}{lcclllll} \text { Column } & \mathbf{n} & \text { Std. dev. } & \text { Median } & \text { Min } & \text { Max } & \text { Q1 } & \text { Q3 } \\ \hline \begin{array}{l} \text { Gas Taxes } \\ \text { (ct/gal) } \end{array} & 51 & 8.1011009 & 46.4 & 30.7 & 68.7 & 40.2 & 51 \\ \hline \end{array} \end{aligned} $$
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