MS 150 Statistics quiz three 4.4 linear regression • Name:

Copper wire
AWG (x)Price \$/ft (y)
140.09
120.15
100.35
80.45
60.45

The table contains the price in dollars per foot of copper wire at Ace Hardware. The price varies with the thickness of the wire, which is reported using the American Wire Gage standard. In the AWG system, the thinner the wire, the higher the AWG number.

1. ______________ How much would fifty feet of AWG 12 wire cost?
2. ______________ Does the relationship between AWG and price appear to be linear, non-linear, or random?
3. ______________ Determine the slope of the linear regression (best fit line) for the data.
4. ______________ Determine the y-intercept of the linear regression for the data.
5. ______________ Determine the correlation coefficient r.
6. ______________ Is the correlation positive or negative?
7. ______________ Is the correlation none, weak, moderate, strong, or perfect?
8. ______________ Determine the coefficient of determination.
9. ______________ What percent in the variation in AWG "explains" the variation in the price?
10. ______________ Use the slope and intercept above to calculate the predicted price for American Wire Gage 4.
11. ______________ Use the slope and intercept to solve for the predicted AWG that will cost four cents (\$0.04).
Linear Regression Functions
Statistic or ParameterMath symbolStat symbolOpenOffice
Slopemb=slope(y-data;x-data)
Interceptba=intercept(y-data;x-data)
Correlation r=correl(y-data;x-data)
Coefficient of Determination r2 =(correl(y-data;x-data))^2