8. Write an equation for a trend line and predict the value when x is 15.
x 0 3 6 9 12
y 17.5 35.4 50,5 60.6 66.3
Pick any two points
(0, 17.5) and (3, 35.4)
Find the slope (35.4-17.5)/(3-0)
17.9/3=5.96666 or 5.97
y = mx+b
17.5 = b since x=0
y = 5.97x + 17.5
replace x with 15 and find y.