Question

Evaluate C_n.xP^xQn-x For the given n=7, x=2, p=1/2

Answer 1

Answer:

The value of given expression is $\frac{21}{128}$.

Step-by-step explanation:

Given information: n=7, x=2, p=1/2

$q=1-p=1-\frac{1}{2}=\frac{1}{2}$

The given expression is

$C(n,x)p^xq^{n-x}$

It can be written as

$^nC_xp^xq^{n-x}$

Substitute n=7, x=2, p=1/2 and q=1/2 in the above formula.

$^7C_2(\frac{1}{2})^2(\frac{1}{2})^{7-2}$

$\frac{7!}{2!(7-2)!}(\frac{1}{2})^2(\frac{1}{2})^{5}$

$\frac{7!}{2!5!}(\frac{1}{2})^{2+5}$

$\frac{7\times 6\times 5!}{2\times 5!}(\frac{1}{2})^{2+5}$

$21(\frac{1}{2})^{7}$

$\frac{21}{128}$

Therefore the value of given expression is $\frac{21}{128}$.