Chapter 2: Problem 11
Briefly explain the three decisions that have to be made to group a data set in the form of a frequency distribution table.
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Chapter 2: Problem 11
Briefly explain the three decisions that have to be made to group a data set in the form of a frequency distribution table.
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A sample of 80 adults was taken, and these adults were asked about the number of credit cards they possess. The following table gives the frequency distribution of their responses. $$ \begin{array}{lc} \hline \text { Number of Credit Cards } & \text { Number of Adults } \\ \hline 0 \text { to } 3 & 18 \\ 4 \text { to } 7 & 26 \\ 8 \text { to } 11 & 22 \\ 12 \text { to } 15 & 11 \\ 16 \text { to } 19 & 3 \\ \hline \end{array} $$ a. Find the class boundaries and class midpoints. b. Do all classes have the same width? If so, what is this width? c. Prepare the relative frequency and percentage distribution columns. d. What percentage of these adults possess 8 or more credit cards?
Briefly explain the concept of cumulative frequency distribution. How are the cumulative relative frequencies and cumulative percentages calculated?
The following table lists the average price per gallon for unleaded regular gasoline in the United States from 1999 to 2008 . $$ \begin{array}{lc} \hline \text { Year } & \begin{array}{c} \text { Average Price per Gallon } \\ \text { (dollars) } \end{array} \\ \hline 1999 & 1.136 \\ 2000 & 1.484 \\ 2001 & 1.420 \\ 2002 & 1.345 \\ 2003 & 1.561 \\ 2004 & 1.852 \\ 2005 & 2.270 \\ 2006 & 2.572 \\ 2007 & 2.796 \\ 2008 & 3.246 \\ \hline \end{array} $$ Draw two bar graphs for these data-the first without truncating the axis on which price is marked, and the second by truncating this axis. In the second graph, mark the prices on the vertical axis starting with $$\$ 1.00 .$$ Briefly comment on the two bar graphs.
How are the relative frequencies and percentages of classes obtained from the frequencies of classes? Illustrate with the help of an example.
The following table, reproduced from Exercise 2.15, gives the frequency distribution of ages for all 50 employees of a company. $$ \begin{array}{lc} \hline \text { Age } & \text { Number of Employees } \\ \hline 18 \text { to } 30 & 12 \\ 31 \text { to } 43 & 19 \\ 44 \text { to } 56 & 14 \\ 57 \text { to } 69 & 5 \\ \hline \end{array} $$ a. Prepare a cumulative frequency distribution table. b. Calculate the cumulative relative frequencies and cumulative percentages for all classes. c. What percentage of the employees of this company are 44 years of age or older? d. Draw an ogive for the cumulative percentage distribution. e. Using the ogive, find the percentage of employees who are age 40 or younger.
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