Chapter 8 Quiz Version B Blank vers
AP Statistics Quiz B – Chapter 8
Name__________________________
In an effort to decide if there is an association between the year of a postal increase and the new postal rate for first class mail, the data were gathered from the United States Postal Service. In
1981, the United States Postal Service changed their rates on March 22 and November 1. This information is shown in the table below.
1. Make a scatterplot and describe the association between the year and the first class postal rate.
Year Rate
1971 0.08
1974 0.10
1975 0.13
1978 0.15
1981 0.18
1981 0.20
1985 0.22
1988 0.25
1991 0.29
1995 0.32
2. Create a model to predict postal rates from the year.
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Copyright 2010 Pearson Education, Inc.
3. Do you think a linear model is appropriate here? Explain.
4. Interpret the slope of your model in context.
5. Interpret the intercept of your model in context.
6. What is the correlation between year and postal rate?
7. Explain the meaning of R2 in the context of this problem.
8. Would it be better for customers for a year to have a negative residual or a positive residual from this model? Explain.
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Copyright 2010 Pearson Education, Inc.
AP Statistics Quiz B – Chapter 8 - KEY
In an effort to decide if there is an association between the year of a postal increase and the new postal rate for first class mail, the data were gathered from the United States Postal Service. In
1981, the United States Postal Service changed their rates on March 22 and November 1. This information is shown in the table below.
1. Make a scatterplot and describe the association between the year and the first class postal rate.
Year
1971
1974
1975
1978
1981
1981
1985
1988
1991
1995
Rate
0.08
0.10
0.13
0.15
0.18
0.20
0.22
0.25
0.29
0.32
There is a strong, positive, linear association between the year and the first class postal rate. Postal rates have increased over time.
2. Create a model to predict postal rates from the year.
ˆ = −19.93 + 0.01015( year )
Rate
8-33
Name__________________________
In an effort to decide if there is an association between the year of a postal increase and the new postal rate for first class mail, the data were gathered from the United States Postal Service. In
1981, the United States Postal Service changed their rates on March 22 and November 1. This information is shown in the table below.
1. Make a scatterplot and describe the association between the year and the first class postal rate.
Year Rate
1971 0.08
1974 0.10
1975 0.13
1978 0.15
1981 0.18
1981 0.20
1985 0.22
1988 0.25
1991 0.29
1995 0.32
2. Create a model to predict postal rates from the year.
8-31
Copyright 2010 Pearson Education, Inc.
3. Do you think a linear model is appropriate here? Explain.
4. Interpret the slope of your model in context.
5. Interpret the intercept of your model in context.
6. What is the correlation between year and postal rate?
7. Explain the meaning of R2 in the context of this problem.
8. Would it be better for customers for a year to have a negative residual or a positive residual from this model? Explain.
8-32
Copyright 2010 Pearson Education, Inc.
AP Statistics Quiz B – Chapter 8 - KEY
In an effort to decide if there is an association between the year of a postal increase and the new postal rate for first class mail, the data were gathered from the United States Postal Service. In
1981, the United States Postal Service changed their rates on March 22 and November 1. This information is shown in the table below.
1. Make a scatterplot and describe the association between the year and the first class postal rate.
Year
1971
1974
1975
1978
1981
1981
1985
1988
1991
1995
Rate
0.08
0.10
0.13
0.15
0.18
0.20
0.22
0.25
0.29
0.32
There is a strong, positive, linear association between the year and the first class postal rate. Postal rates have increased over time.
2. Create a model to predict postal rates from the year.
ˆ = −19.93 + 0.01015( year )
Rate
8-33