20. A local children's center has 47 children enrolled, and 6 are selected to take a picture for the center's advertisement. How many ways are there to select the 6 children for the picture?
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Given:
Total number of children enrolled = 47
Number of children to be selected = 6
Number of ways to select 6 children for the picture are:
[tex]=^{47}C_6[/tex]Formula for combination is given as:
[tex]^nC_r=\frac{n!}{r!(n-r)!}[/tex]Applying this, we get:
[tex]\begin{gathered} ^{47}C_6=\frac{47!}{6!(47-6)!} \\ =\frac{47!}{6!41!} \\ =10737573 \end{gathered}[/tex]Therefore, the required number of ways are 10737573.