SOLUTION: How many trials were conducted in a binomial distribution which has a mean of 8 and standard deviation of 2?

mean = n·p

standard deviation = √n·p·(1-p)

n·p = 8

√n·p·(1-p) = 2

Square both sides of the second equation:

(√n·p·(1-p))² = (2)²

n·p(1-p) = 4

Substitute 8 for n·p

8(1-p) = 4

8-8p = 4
 -8p = -4
   p = 0.5

    n·p = 8
n·(0.5) = 8
      n = 
      n = 16

Edwin