Class

In the 7C class, there are ten girls and 20 boys. Yesterday was missing 20% of girls and 50% of boys. What percentage of students are missing?

Correct answer:

x =  40 %

Step-by-step explanation:

$$\begin{gathered} g=10 \\ b=20 \\ {q}_1=20\%=\frac{20}{100}=\frac{1}{5}=0.2 \\ {q}_2=50\%=\frac{50}{100}=\frac{1}{2}=0.5 \\ x=100\cdot \frac{q_1\cdot g+q_2\cdot b}{b+g}=100\cdot \frac{0.2\cdot 10+0.5\cdot 20}{20+10}=40\% \end{gathered}$$

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