To find the cost per pound of the chicken, you need to divide the total cost by the number of pounds purchased.
Raphael bought 2 1/2 pounds of chicken for $9.00.
First, convert 2 1/2 pounds to an improper fraction or decimal: 2 1/2 = 2 + 1/2 = 2 + 0.5 = 2.5 pounds.
Now, divide the total cost by the number of pounds:
\[ \text{Cost per pound} = \frac{\text{Total Cost}}{\text{Total Pounds}} = \frac{9.00}{2.5} \]
Now, perform the division:
\[ \frac{9.00}{2.5} = 3.60 \]
Thus, the cost per pound of the chicken is $3.60.