Question

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

Answer 1

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.

Answer 2

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`