We will consider x on the graph to be years since 1990 and y on the graph to be the number of Moose.
We have two points on the graph: (4, 4290) and (8, 3850)
Using the slope formula (m = [y2 - y1]/[x2 - x1]), we can find the slope of this line:
m = (y2 - y1)/(x2 - x1) Slope formula
m = (3850 - 4290)/(8 - 4) Substitution
m = -440/4 Solve the subtraction problems in the parenthesis
m = -110 Reduce the fraction
Now that we have the slope of the line, we can use the point-slope formula (y - y1 = m[x - x1]) to find the equation for the line. I will use the first point, but either point will produce the same answer.
y - y1 = m(x - x1) Point-slop e formula
y - 4290 = -110(x - 4) Substitution
y - 4290 = -110x + 440 Distribute the -110
y - 4290 + 4290 = -110x + 440 + 4290 Add 4290 to each side
y = -110x + 4730 Simplify
Since the formula that is being sought is supposed to be interms of P and t, I will replace y with P and x with t.
P(t) = -110t + 4730
To predict the population in 2006, we need to determine the years from 1990 to 2006.
2006 - 1990 = 16
P(16) = -110 (16) + 4730
P(16) = -1760 + 4730
P(16) = 2970