I need help on this question

Question

The amount of money, in dollars, Sarah has in her savings account is modeled as a function of time in months. This function is represented by the graph below.

What is the average rate of change for the amount of money, in dollars per month, from month 0 to month 12

1. $25 per month
2. $300 per month
3. $500 per month
4. $50 per month

Answer 1

If you look at the "rise" (Y value), it goes from $200 to $500. This is a total increase of $300 over 12 months. So you would take the total difference ($300) divided by 12 (months) to get the rate of money gained per month (average).

300/12 = $25/ 1 month

Another way to write it would be: (500-200) / (12-0) = 200/12 = 25

Answer 2

Rise/run

(500-200)/(12-0) = your answer