Peaches

There are 20 peaches in the pocket. Three peaches are rotten. What is the probability that one of the randomly picked two peaches will be just one rotten?

Correct answer:

p =  0.2684

Step-by-step explanation:

$$\begin{gathered} C_2(20)=\left(\genfrac{}{}{0ex}{}{20}{2}\right)=\frac{20!}{2!(20-2)!}=\frac{20\cdot 19}{2\cdot 1}=190 \\ n=20 \\ a=3\cdot (n-3)=3\cdot (20-3)=51 \\ b=\left(\genfrac{}{}{0ex}{}{n}{2}\right)=190 \\ p=a/b=51/190=0.2684 \end{gathered}$$

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