## Intermediate Algebra (12th Edition)

To calculate the average rate of change between two points $(x_1,y_1)$ and $(x_2,y_2)$, we use the formula: $\displaystyle average~rate~of~change=\frac{y_2-y_1}{x_2-x_1}$ Here, we use the points $(1990, 4.23)$ and $(2012, 7.96)$: $\displaystyle average~rate~of~change=\frac{7.96-4.23}{2012-1990}=\frac{3.73}{22}=0.17~dollars/year=17~cents/year$ Thus the average price of a movie ticket increased by 17 cents/year from 1990 to 2012.