2. Describing Data with Tables and Graphs

Given the following frequency distribution for exam scores: $50-59$: $3$ students, $60-69$: $5$ students, $70-79$: $8$ students, $80-89$: $4$ students, which of the following represents the correct cumulative frequency for the class interval $70-79$?

Which of the following best describes the difference between $relative frequency$ and $cumulative frequency$ in a frequency distribution?

Why is it generally recommended that the number of classes in a frequency distribution be between $5$ and $20$?

In a relative frequency distribution, what does each $f/n$ (relative frequency) represent?

In Exercises 23 and 24, construct the relative frequency distributions and answer the given questions.

Oscar Winners Construct one table (similar to Table 2-5) that includes relative frequencies based on the frequency distributions from Exercises 5 and 6, and then compare the ages of Oscar-winning actresses and actors. Are there notable differences?

Use the frequency distribution below to find the class width and class midpoints.

The following data set shows the number of overtime hours that 12 employees worked in a month. Construct a frequency distribution, using a lower class limit of 3 and a class width of 4.

A data set has a minimum value of 16 and a maximum value of 71. Without constructing a table, find the class width if you organized this data into 7 classes. Write the lower and upper class limits.

min = 16; max = 71; 7 classes.

In Exercises 5–8, identify the class width, class midpoints, and class boundaries for the given frequency distribution. Also identify the number of individuals included in the summary. The frequency distributions are based on real data from Appendix B.

Boston Commute Time The accompanying table summarizes daily commute times in Boston. How many commute times are included in the summary? Is it possible to identify the exact values of all of the original data amounts?

In Exercises 5–8, identify the class width, class midpoints, and class boundaries for the given frequency distribution. Also identify the number of individuals included in the summary. The frequency distributions are based on real data from Appendix B.

7.

In Exercises 5–8, identify the class width, class midpoints, and class boundaries for the given frequency distribution. Also identify the number of individuals included in the summary. The frequency distributions are based on real data from Appendix B.

8.

In Exercises 9–12, using a loose interpretation of the criteria for determining whether a frequency distribution is approximately a normal distribution, determine whether the given frequency distribution is approximately a normal distribution. Give a brief explanation.

Best Actors Refer to the frequency distribution from Exercise 6

Presidents Listed below are the ages (years) of presidents of the United States at the times of their first inaugurations (from Data Set 22 “Presidents” in Appendix B). Presidents who took office as a result of an assassination or resignation are not included. The data are current as of this writing. Use these ages to construct a frequency distribution. Use a class width of 5 years and begin with a lower class limit of 40 years. Do the ages appear to have a normal distribution?

Tornadoes Listed below are the F-scale intensities of recent tornadoes in the United States. Construct a frequency distribution. Do the intensities appear to have a normal distribution?