Question

If n = 10 and p = 0.70, then the standard deviation of the binomial distribution is

Answer 1

For a binomial distribution, the variance is
$\sigma^2=npq=np(1-p)=10*0.7*0.3=2.1$
$\sigma=standard\,deviation=\sqrt{2.1}=1.449$ (to 3 decimal places)