We know for a binomial distibution with probability
function,
P(x = r) = nCr * p^r *(1-p)^(n-r), the mean = np
and variance = np(1-p).
Standard deviation, s=
(variance)^(1/2) ={np(1-p)}^(1/2).
Standard deviation , s
= (np(1-p)}^(1/2)....(1)
So we substitute n = 2815, p =
0.63, in the formula at (1).
Standard deviation =
{2815*0.63*(1-0.63)}^(1/2).
Standard deviation =
{2815*0.63*0.37}^(1/2) = 25.6159 = 25.62.
So the required
standard deviation for the give binomial distribution is 25.62
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