A2. In a pond, there are red and yellow carps. Two fifths of the carps are yellow, the rest are red. Three quarters of the yellow carps are female. In total, there are as many female carps as male carps.

What part of the total carp population consists of red male carps?
A) $\frac{1}{5}$
B) $\frac{1}{4}$
C) $\frac{3}{10}$
D) $\frac{2}{5}$
E) $\frac{1}{2}$
A2. D) $\frac{2}{5}$ From the data, we deduce that $\frac{2}{5} \cdot \frac{3}{4}=\frac{3}{10}$ of the carp are yellow females. Since half of the carp are females, we find that $\frac{1}{2}-\frac{3}{10}=\frac{1}{5}$ of the carp are red females. If we then finally use the fact that three fifths of the carp are red, we find that $\frac{3}{5}-\frac{1}{5}=\frac{2}{5}$ of the carp are red males.