1. The equation of the line of best fit is: y = -1.15x + 102.8
2. Using the equation of the line of best fit, the predicted cost is: $62.55
What is the Equation of a Line of Best Fit?
The equation of a line of best fit is represented by the equation, y = mx + b, where m is the slope and b is the initial value.
1. Using two points, (72, 20) and (20, 80):
Slope (m) = change in y / change in x = (80 - 20)/(20 - 72) = 60/-52
Slope (m) = -1.15.
Substitute m = -3 and (a, b) = (72, 20) into y - b = m(x - a)
y - 20 = -1.15(x - 72)
y - 20 = -1.15x + 82.8
y = -1.15x + 82.8 + 20
y = -1.15x + 102.8
The equation of the best line of fit is y = -1.15x + 102.8.
2. Monthly heating cost, y, for a month with an average temperature of 35°F (x) will be calculated by substituting x = 35 into y = -1.15x + 102.8.
y = -1.15(35) + 102.8
y = 62.55
The predicted monthly cost is $62.55.
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