An examination

In an examination there were 1000 boys and 800 girls. 60% of the boys and 50% of the girls passed. Find the percent of candidates failed.

Correct answer:

p =  44.4444 %

Step-by-step explanation:

$$\begin{gathered} a=1000 \\ b=800 \\ n=a+b=1000+800=1800 \\ {p}_1=60\%=\frac{60}{100}=\frac{3}{5}=0.6 \\ {p}_2=50\%=\frac{50}{100}=\frac{1}{2}=0.5 \\ x=p_1\cdot a+p_2\cdot b=0.6\cdot 1000+0.5\cdot 800=1000 \\ y=n-x=1800-1000=800 \\ p=100\cdot \frac{y}{n}=100\cdot \frac{800}{1800}=\frac{100\cdot 800}{1800}=\frac{80000}{1800}=44.4444\% \end{gathered}$$

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