MAT 107 Extra Credit Problem:

Due: at the beginning of class Tuesday 10/26/04

Directions: Answer the following questions using the given data. You are to work on this INDEPENDENTLY! Sign the bottom of this sheet and hand it in with your work. Work should be done neatly and clearly, preferably typed. Complex mathematical calculations should be done on a computer or calculator.

A researcher is interested in predicting gas mileage from the weight of a car. The data below is a random sample of 20 cars: their weights are given in thousands of pounds and their gas mileages given in mpg. Create a scatter plot of the data. Comment on whether the data looks linear. Find the regression line. Interpret the slope in the words of the problem. Find r ². Interpret r ² in the words of the problem. Does the regression line do a good job of predicting gas mileage from car weight? You should use r ² and some actual and predicted values to justify your answer.

Weight	MPG
2.6	44
3.5	38
3.6	34
3.7	37
4.1	34
4.2	35
4.3	35
4.5	34
4.6	33
4.8	33
4.9	31
5.2	31
5.6	30
5.6	31
5.8	29
6.0	28
6.1	30
6.2	29
6.5	24
9.8	15

I certify that all work done on this extra credit is my own. Any knowledge used, was obtained from class, the text, or other statistics texts. I did not discuss my work or answers with anyone else taking MAT 107 with Professor Mugno.

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Signature Date