I have choose the MINI Cooper for my chapter 2 project. I found out the mileage for the car in http://www.mpgforspeed.com/. For the speeds 55, 60, 65, 70, 75, 80 in miles per hour, the mileage (miles per gallon) are 37, 35.9, 34, 30.7, 28.5, 26.6 . Next I plot the points using speed as the independent variables and the mileage as the dependent variables. Since the points are going down, the graph have a negative slope that mean it also have a

**negative correlation**. Next, I sketch the

**line best fit**on the graph. The 2 points I choose to find the slope with is (60,35.9) and (80,26.6); doing the calculation

*Y1 - Y2*over

*X1 - X2*I got the

**slope**-9.3/20. To use the informations I already have to write an equation I set up the

**point-slope form**first which

*is*y

*-26.6=-9.3/20(x-80)*turning it to slope-intercept form the equation is y=-9.3/20

*x+63.8 .*Using the calculator to find the value of

**correlation coefficient r**,

*r=-.9917995234.*The value of r tell me that the as speed get higher is the mileage will go lower, because

*r*is close

**-1 coefficient**. By using the graphing calculator to find the

**equation**for

**the line best fit**I get

*y=-.4428571429x+62.00952381*. To predict the mileage for a speed of 55 miles per hour, I type in :

*y(55)*in my calculator, the

**mileage is 38 (miles per gallon).**To predict the speed if the milage is 28 miles per gallon we can't use the same method because 28 is

*y*in the equation, so I plug 28 in as

*y, 28=-.4428571429x+62.00952381.*After isolating

*x (speed)*the answer is

**77 miles per hour.**

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