91Ó°ÊÓ

$9$ percent of Internet users download music files from the internet, $21\%$ share music files from their PCs, and $12\%$ download and share music simultaneously.

The fraction of internet users who download music files from the internet and distribute music files from their computers is of relevance here. $29$percent of internet users download music files from the internet, while $21\%$exchange music files and $12\%$do both. They also understand that the table must comprise $100$percent of all internet users.

Using the known row/column, the remaining percentages may be calculated.

From the previous solution

The percentage of internet users who do not download or share music files is provided in the table above in the row "do not share music files" and column "do not download online," which is $62$percent.

From the previous solution

$$\begin{gathered} P(downloadonline)=29\%=0.29 \\ P(sharemusicfileanddownloadonline)=12\%=0.12 \\ P\left(B\right|A)=\frac{P(Aâˆ\copyright B)}{P\left(A\right)} \\ =\frac{P(sharemusicfileanddownloadonline)}{P(downloadonline)} \\ =\frac{0.12}{0.29} \\ =0.4138 \\ =41.38\% \end{gathered}$$