Table of contents
- 1. Intro to Stats and Collecting Data55m
- 2. Describing Data with Tables and Graphs1h 55m
- 3. Describing Data Numerically1h 45m
- 4. Probability2h 16m
- 5. Binomial Distribution & Discrete Random Variables2h 33m
- 6. Normal Distribution and Continuous Random Variables1h 38m
- 7. Sampling Distributions & Confidence Intervals: Mean1h 3m
- 8. Sampling Distributions & Confidence Intervals: Proportion1h 12m
- 9. Hypothesis Testing for One Sample1h 1m
- 10. Hypothesis Testing for Two Samples2h 8m
- 11. Correlation48m
- 12. Regression1h 4m
- 13. Chi-Square Tests & Goodness of Fit1h 20m
- 14. ANOVA1h 0m
2. Describing Data with Tables and Graphs
Frequency Distributions
Problem 2.1.14
Textbook Question
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?


1
Step 1: Organize the data by listing the ages of the presidents at their first inauguration. The ages provided are: 57, 61, 57, 57, 61, 64, 48, 49, 64, 52, 46, 49, 47, 55, 42, 51, 56, 51, 54, 60, 62, 43, 55, 56, 52, 69, 46, 54, 47, 70.
Step 2: Determine the range of the data by identifying the minimum and maximum ages. The minimum age is 42 and the maximum age is 70.
Step 3: Create the class intervals for the frequency distribution. Start with a lower class limit of 40 years and use a class width of 5 years. The classes will be: 40-44, 45-49, 50-54, 55-59, 60-64, 65-69, and 70-74.
Step 4: Count the number of ages that fall into each class interval to construct the frequency distribution. For example, count how many ages fall between 40 and 44, then 45 and 49, and so on.
Step 5: Analyze the frequency distribution to determine if the ages appear to have a normal distribution. A normal distribution typically has a bell-shaped curve, so check if the frequencies increase to a peak and then decrease symmetrically.

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