Simple Rate of Change

Jasper has invested an amount of money into a savings account. The graph below shows the value of his investment over a period of time. What is the rate of change for the interval [1, 3]?
  1. Determine the interval to be observed.
  2. Identify the starting point of the interval.
  3. Identify the ending point of the interval.
  4. Substitute the starting point and ending point into the slope formula to calculate the rate of change.