What is the variance of a binomial distribution for which n = 75 and p = 0.20?

2 Answers
Nov 1, 2015

75 x (1/5) x (4/5)

Explanation:

The formula for the variance of a binomial distribution is n x p x q where q = 1 - p. Here n = 75, p = .20 or (1/5) and q = 0.80 or (4/5) and hence the answer.

Nov 1, 2015

The answer is 12.

Explanation:

Note that if X~ "Bin ( n , p )" then Variance of X is np(1-p).

Now your n = 75 and p = 0.20 .

So your variance = 75 times 0.20 times ( 1 - 0.20 ) = 75 times 0.20 times 0.80 =12