Answer:
The number of ways to choose a set of 9 pencils from a selection of 10 is 10.
Step-by-step explanation:
According to the combination formula, the total number of ways to select r items from total n items is
\(^nC_r=\frac{n!}{r!(n-r)!}\)
Total number of pencils = n = 10
Number of selected pencils = r = 9
The number of ways to choose a set of 9 pencils from a selection of 10 is
\(^{10}C_{9}=\frac{10!}{9!(10-9)!}\)
\(^{10}C_{9}=\frac{10\times 9!}{9!1!}\)
\(^{10}C_{9}=10\)
Therefore the number of ways to choose a set of 9 pencils from a selection of 10 is 10.
