Boys and girls

There are 11 boys and 18 girls in the classroom. Three pupils will answer. What is the probability that two boys will be among them?

Correct answer:

p =  27.0936 %

Step-by-step explanation:

$$\begin{gathered} n=11+18=29 \\ {C}_2(3)=\left({\displaystyle \genfrac{}{}{0px}{}{3}{2}}\right)={\displaystyle \frac{3!}{2!(3-2)!}}={\displaystyle \frac{3}{1}}=3 \\ p=100\cdot \left(\genfrac{}{}{0px}{}{3}{2}\right)\cdot {\displaystyle \frac{11}{n}}\cdot {\displaystyle \frac{10}{n-1}}\cdot {\displaystyle \frac{18}{n-2}}=100\cdot 3\cdot {\displaystyle \frac{11}{29}}\cdot {\displaystyle \frac{10}{29-1}}\cdot {\displaystyle \frac{18}{29-2}}={\displaystyle \frac{5500}{203}}\mathrm{\%}=27.0936\mathrm{\%} \end{gathered}$$

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Math student

Answer is not accurate.correct answer is .2679076632908277

1 year ago  Like

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