Question

At a large midwestern college, 4% of the students are hispanic. a random sample of 20 students from the college is selected. let x denote the number of hispanics among them. the standard deviation of x is:

Answer 1

Binomial distribution is used 
Standard deviation = $\sqrt{n*p*q}$
where
$n=20$ 
$p=4$% $=0.04$ 
$q = 1 - p = 1 - 0.04 = 0.96$

Standard deviation = $\sqrt{(20*0.04*0.96) }$
$\sqrt{0.768} \\ =0.876$

Therefore
The answer is
$0.876$