Question

If X ∼ B`(20, 1/10)` then Var(X) = ______.

Options

• `9/5`

• 2

• `5/9`

• `1/2`

Answer 1

If X ∼ B`(20, 1/10)` then Var(X) = `bbunderline(9/5)`.

Explanation:

Given: n = 20, p = `1/10`

Var(X) = n × p × (1 − p)

= `20 xx 1/10 xx (1 - 1/10)`

= `20 xx 1/10 xx 9/10`

= `2 xx 9/10`

= `18/10`

= `9/5`