Friday, October 29, 2010

Ch 2 Project

For my Ch. 2 Project. I picked the car model Ferrari California. First I found out the mileage (miles per gallon) as the speed is at 55,60,65,70,75,and 80. Then I plotted the points on the graph. The graph was a negative correlation so it was going to have a negative slope. Then I drew the line of best fit. I found out the two points of the line of best fit and found the slope to be -5.3/25x. Then I used the point-slope form(y-y1=slope(x-x1) to write an equation. It turned out to be y=-5.3/25x+30.66. I plugged in all the plots to my graphing calculator to find out the correlation coefficient r(R=1 is postivite and R=-1 is a negative) and it was R=-.991. The R value tells that if you drive faster miles per gallon goes down, and that the graph is a negative correlation with almost a -1 coefficient, which is a straight negative line. I found that in the calculator the line of best fit(y=ax+b) was; a=-.2262857143, b=21.77428571. I plugged in if the speed of the car goes 55 miles per hour it would be -5.3/25(55)+30.66 which equals to 19 mpg and my prediction if the speed is 28 miles per hour it would be 40mph

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