Question 811841
Question 811841
How many trials were conducted in a binomial distribution which has a mean of 8 and standard deviation of 2?
<pre>
mean = n·p

standard deviation = &#8730;<span style="text-decoration: overline">n·p·(1-p)</span>

n·p = 8

&#8730;<span style="text-decoration: overline">n·p·(1-p)</span> = 2

Square both sides of the second equation:

(&#8730;<span style="text-decoration: overline">n·p·(1-p)</span>)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 = {{{8/0.5}}}
      n = 16

Edwin</pre>