## Tuesday, November 9, 2010

### Ch 2 project- Ford Mustang

For my chapter 2 project, I chose the Ford Mustang. The mileage for the speeds: 55, 60, 65, 70, 75, and 80 were 30, 29.1, 27.6, 24.9, 23.1, and 21.6. I knew I had a negative correlation because I had a negative slope. Then I sketched the line of best fit, while trying to get as many points on the line as possible. I then chose 2 points on the graph, (80, 21.6) and (70, 24.9), and found the slope (by using the slope formula) which was -.33. Then to find the equation I had to use the point slope form, then turning it into slope intercept form and I got y= -.33x + 48. I had to use the calculator to find the correlation coefficient r and got r= -.9914. This told me that as the speed gets higher the mileage will get lower, because it’s reaching the – 1 coefficient. Also when using the calculator I was able to find the equation for the line of best fit, which was y= -.3582x + 50.2342. To predict the mileage for a speed of 55 mph, I plugged in 55 for X and solved for y and I got 30.5332 miles per gallon. To predict the speed if the mileage is28 I plugged in 28 for y and solved for x and I got 62.87202 miles per hour.