# What are the mean and standard deviation of a binomial probability distribution with n=7  and p=19/21 ?

Mean of the distribution $= n p = 7 \times \frac{19}{21} = 6 \frac{1}{3}$
Standard Deviation $= \sqrt{n p q} = \sqrt{7 \times \frac{19}{21} \times \frac{2}{21}} = \sqrt{\frac{38}{63}} = 0.7766$