# What are the mean and standard deviation of a binomial probability distribution with n=9  and p=11/32 ?

Dec 6, 2015

mean $= n p$

s.d. $= \sqrt{n p q}$

#### Explanation:

Using the formula for mean and s.d. above ...

mean $= 9 \times \frac{11}{32} = \frac{99}{32} \approx 3.09$

s.d. $= \sqrt{9 \times \frac{11}{32} \times \left(1 - \frac{11}{32}\right)} \approx 1.425$

hope that helped