Exam 4: Graphical Descriptive Techniques Numerical Data

Class intervals of equal width make the interpretation of a frequency distribution easier.

Compared to the frequency distribution, the stem-and-leaf display provides more details, since it can describe the individual data values as well as show how many are in each group, or stem.

Which of the following is the most important and commonly used graphical presentation of numerical (quantitative) data?

Which of the following is the most appropriate type of chart for determining the number of observations at or below a specific value?

If two numerical variables are linearly related, then it means that an increase in one variable is causing the other variable to decrease.

Which of the following statements is false?

The difference between a histogram and a bar chart is that the histogram represents numerical (quantitative) data while the bar chart represents nominal (categorical) data.

The number of houses sold in a suburb in Sydney and the average monthly mortgage rates for 18 months randomly selected are shown in the following table. Mortgage rate (\%) Number of houses sold Mortgage rate (\%) Number of houses sold 7.5 90 9.5 68 9.0 72 6.5 97 7.0 89 8.0 79 10.5 62 9.0 75 10.0 58 10.5 53 9.5 70 9.5 73 8.5 74 11.0 50 10.0 65 7.5 82 11.0 51 8.5 70 a. Draw a scatter diagram with the number of houses sold on the vertical axis. b. Describe the relationship between mortgage rate and number of houses sold.

Which of the following is the sum of the relative frequencies for all classes?

The relationship between expenditure on imports and household income may be described as a positive linear relationship.

A histogram is said to be symmetric if, when we draw a vertical line down the center of the histogram, the two sides are mirror images of each other.

Construct an ogive for the test grades for a university business statistics class, and estimate the proportion of grades that are between 80 and 90. 63 74 42 65 51 54 36 56 68 57 62 64 76 67 79 61 81 77 59 38 84 68 71 94 71 86 69 75 91 55 48 82 83 54 79 62 68 58 41 47

The lowest value in a set of data is 140, and the largest value is 270. If the resulting frequency distribution is to have ten classes of equal width, the common class width will be 27.

The graphical format used to display the relationship between two numerical (quantitative) variables is the scatter diagram.

A cumulative frequency distribution presented in graphical form is called an ogive.

Which of the following statements best describes a stem-and-leaf display?

The numbers of defective items produced by a machine over the last 25 days are as follows: 19 6 15 20 17 16 17 12 15 29 23 17 7 10 14 14 27 22 8 5 23 19 9 28 5 a. Construct a frequency distribution and a relative frequency distribution for these data. Use five class intervals, with the lower boundary of the first class being five items. b. Construct a relative frequency histogram for these data. c. What is the relationship between the total area under the histogram you have constructed and the relative frequencies of observations?

A cumulative frequency distribution lists the proportion of observations that are within or below each of the classes.

Which of the following may be determined from the height of the bar in a relative frequency histogram?

A skewed histogram is one with a long tail extending either to the right or left. The former is called negatively skewed, and the latter is called positively skewed.