In a warehouse, a dozen eggs and 10 apples had the same price. After a week, the price of eggs fell by $2 \%$ and the price of apples rose by 10\%. How much more will be spent on the purchase of a dozen eggs and 10 apples?
(a) $2 \%$
(b) $4 \%$
(c) $10 \%$
(d) $12 \%$
(e) $12.2 \%$
We can assume that the initial price of a dozen eggs is $R \$ 1.00$, so 10 apples also cost $R \$ 1.00$. Since the price of eggs has dropped by $2 \%$, the new price of a dozen eggs is $R \$ 0.98$. The price of apples has increased by $10 \%$, so the new price of 10 apples is $R \$ 1.10$. Thus, before it cost $R \$ 2.00$ to buy eggs and apples, and now it costs $0.98+1.10=2.08$ reais. Therefore, the increase was $R \$ 0.08$, which corresponds to $\frac{0.08}{2} \times 100 \% = 4 \%$. The correct option is (b).