Answer:
a) The easiest way is to use a calculator such as a Casio brand or Sharp brand and key in 9C7 to get 36.
However, you can also use this formula: [tex]nCr=\frac{n!}{r!(n-r)!}[/tex] where n is the total number of items and r is how many you are selecting.
Plug in values:
[tex]\frac{9!}{7!(9-7)!} =\frac{9!}{7!*2!}=\frac{9*8}{2!}=36[/tex]
b) The easiest way is to use a calculator such as a Casio brand or Sharp brand and key in 9P7 to get 181440.
However, you can also use this formula: [tex]nPr=\frac{n!}{(n-r)!}[/tex] where n is the total number of items and r is how many you are selecting.
Plug in values:
[tex]\frac{9!}{(9-7)!} =\frac{9!}{2!}=9*8*7*6*5*4*3=181440[/tex]
