Introduction to Statistics



Introduction to Statistics

Displaying and Describing Quantitative Data (Ch. 4)

The plot below shows the life expectancy at birth for people born in the United States between 1920 and 1990. It is called a timeplot (plot over time).

1. What is the life expectancy of black females born in 1920?

2. Which group had the greatest increase in life expectancy between 1940 and 1950? How can you tell from the timeplot?

3. What happened to the life expectancy of males born between 1960 and 1970?

4. Explain what the plot indicates happened where two of the graphs crossed.

5. What is the overall trend with life expectancies?

Each year Consumer Reports provides ratings of automobile repair records. The table below contains those rating for several cars. A 5 represents few repairs, and a 1 many repairs.

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6. What does a rating of 4.14 for the 1993 LeBaron indicate about the repair rating for the car?

7. Which 1989 car had the fewest problems?

Plotting an event over time allows you to see trends and make comparisons. The horizontal axis usually represents time. In this plot, the horizontal axis indicates the time the car was built and the vertical axis gives the repair rating.

8. What type of car is the graph representing?

9. Between which two years did the Accord make the largest gain in ratings? How can you tell?

10. Did the ratings ever decline over time? If so, when?

11. Did the ratings ever remain the same from year to year? If so, when?

12. Using the timeplot, estimate an average rating for the Accord over the 7 year time period.

13. Describe the change in the ratings over the 7 year period.

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