Katie earned 1200 in 8 years on an investment at a 6% annual simple interest rate. how much was katie's investment?

a) Differences between x-values are constant (2), and differences between y-values are also constant (10), so the model can be a linear equation. It will have a slope of (10)/(2) = 5. We can use any of the table value pairs in the pont-slope form of the equation:

 y = 5(x -3) +15

or

 y = 5x

b) The model predicts the height at 12 months will be

 y = 5·12

 y = 60

We assume x represents months. The units for y are not given in this problem statement.