13. (15 points) The supermarket purchases 500 kg of tangerine peels, with a purchase price of 4.80 yuan per kilogram, and the expected weight loss is 10%. If the supermarket hopes to make a profit of 20% on selling this batch of tangerine peels, what should be the retail price per kilogram of the tangerine peels?
【Solution】Solve: $500 \times 4.8 \div(500-500 \times 10 \%) \times(1+20 \%)$
$$
\begin{array}{l}
=2400 \div 450 \times 1.2 \\
=6.4 \text{ (yuan) }
\end{array}
$$

Answer: The retail price per kilogram of tangerine should be set at 6.4 yuan.