To find the rate of change (slope) of the cost of broccoli in dollars per pound based on the given points (3, 8.25) and (6, 16.50), we can use the slope formula:
\[ \text{slope} = \frac{y_2 - y_1}{x_2 - x_1} \]
Here, \( (x_1, y_1) = (3, 8.25) \) and \( (x_2, y_2) = (6, 16.50) \).
Now we can plug in the values:
\[ \text{slope} = \frac{16.50 - 8.25}{6 - 3} \]
Calculating the differences:
\[ = \frac{16.50 - 8.25}{3} = \frac{8.25}{3} = 2.75 \]
Thus, the rate of change in the purchase price of broccoli is $2.75 per pound.