a typical jersey cow weighs 150 lb at 3 mos. and 540 at 15 mos. what would be a point slope equation for this?

Question

a typical jersey cow weighs 150 lb at 3 mos. and 540 at 15 mos. what would be a point slope equation for this, giving the weight of the cow as the function?

Answer 1

We assume the cow gets heavier at a steady (linear) rate:

(y2 - y1) / (x2 - x1)

We'll take the x-axis to represent time and the y-axis to represent weight.

(540 - 150) / (15 - 3) = 32.5

This is our slope. Now we align it with one of our points -- I'll choose the lower point (3, 150).

y - y1 = m(x - x1)
y - 150 = 32.5(x - 3)
y = 32.5x - 97.5 + 150
y = 32.5x + 52.5

And that last one should be your equation!

Answer 2

Points are (3 , 150) and (15 , 540)
slope = 390 / 12 = 130 / 4 = 65 / 2
W = weight
M = months
W - 150 = (65 / 2) (M - 3)
W = (65 / 2) M - 195 / 2 + 150
W = (65 / 2) M + 105 / 2