Binomial Distribution question If someone would please show

Binomial Distribution question!

If someone would please show me how to solved this question??

A binomial distribution has a mean of 8 and a standard deviation of 2. The number of trials is what number?

Solution

mean = np = 8

note q = 1 - p

standard deviation = sqrt( n*p*q ) = 2

= sqrt(8q) = 2

8q = 4

q=.5

Since q = 1 - p, p is .5 as well.

np = 8 = n*.5 => n=16