Problem (Algebra):
A bakery sells small and large cookies. Before a price increase, the price of each small cookie is $\$ 1.50$ and the price of each large cookie is $\$ 2.00$. The price of each small cookie is increased by $10 \%$ and the price of each large cookie is increased by $5 \%$. What is the percentage increase in the total cost of a purchase of 2 small cookies and 1 large cookie?

Solution:
Before the price increase, the total cost of 2 small cookies and 1 large cookie is $2 \cdot \$ 1.50+\$ 2.00=\$ 5.00$.

$10 \%$ of $\$ 1.50$ is $0.1 \cdot \$ 1.50=\$ 0.15$. After the price increase, 1 small cookie costs $\$ 1.50+\$ 0.15=\$ 1.65$.

$5 \%$ of $\$ 2.00$ is $0.05 \cdot \$ 2.00=\$ 0.10$. After the price increase, 1 large cookie costs $\$ 2.00+\$ 0.10=\$ 2.10$.

After the price increase, the total cost of 2 small cookies and 1 large cookie is $2 \cdot \$ 1.65+\$ 2.10=\$ 5.40$.

The percentage increase in the total cost is $\frac{\$ 5.40-\$ 5.00}{\$ 5.00} \times 100 \%=\frac{40}{500} \times 100 \%=8 \%$.

Final answer: $8 \%$