One-quarter 6369

According to research, one-quarter of pupils will encounter drugs at the end of primary school. Of this number, 40% of pupils try the drug. How many students attend Year 9 if 12 have signed up to use drugs?

Correct answer:

n =  120

Step-by-step explanation:

$$\begin{gathered} r_1=1/4=\frac{1}{4}=0.25 \\ {r}_2=40\%=\frac{40}{100}=\frac{2}{5}=0.4 \\ n\cdot r_1\cdot r_2=12 \\ n\cdot 0.25\cdot 0.4=12 \\ 0.1n=12 \\ n=\frac{12}{0.1}=120 \\ n=120 \end{gathered}$$

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