Question

A blood bank needs 8 people to help with a blood drive. 11 people have volunteered.

Answer 1

Answer: 1584

Step-by-step explanation:

The number of ways to choose r people out of n is given by Combination ( where order does not matter) and the formula to find them is

$C(n,r)=\frac{n!}{r!(n-r)!}$

Now , it is given that

A blood bank needs 8 people to help with a blood drive. 11 people have volunteered.

Then, the number of different groups of 8 can be formed from the 11 volunteers =

$C(11,9)=\frac{11!}{8!(11-8)!}$

$=\frac{11*10*9*8}{8!3!}$

$=\frac{7920}{5}$

$=1584$

Hence, the number of different groups of 8 can be formed from the 11 volunteers = 1584

Answer 2

Answer:

165

Step-by-step explanation:

formula is

nCr = n!/(r!(n−r)!)

r= 8 = number of choosing objects from the set

n = 11 = total number of objects in the set

C(n,r)=C(11,8)

=11!/(8!(11−8)!)

! means factorial

factorial means to multiply by decreasing positive numbers.

For example, 8! = 8 ∗ 7 ∗ 6 ∗ 5 ∗ 4 ∗ 3 ∗ 2 ∗ 1 = 40320

=11!/8!×3!

= 165

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