3.89 cents per ounce
Explanation
to solve this we need to do a conversion of units,
the equivalences are
[tex]\begin{gathered} \text{ 1 \$ }\rightarrow100\text{ cents} \\ \end{gathered}[/tex]so
Step 1
find the cost in dollars
to know the cost in cents, just multiply the cost in dollars by 100
hence
[tex]\begin{gathered} \text{cost}_{cents}=2.49\cdot100=249 \\ \text{cost}_{cents}=249\text{ cents} \end{gathered}[/tex]Step 2
now, find the rate
the rate is given by.
[tex]rate=\frac{\text{cost( cents) }}{\text{amount( ounces)}}[/tex]now, replace
[tex]rate=\frac{249\text{ cents}}{64\text{ ounces}}=3.89\text{ cents per ounce}[/tex]therefore, the answer is
3.89 cents per ounces
I hope this helps you
