Question

In a National Achievement Test, suppose three test

booklets are tested at random. Let D represent the

defective test booklet and let N represent the

non-defective test booklet. Let X be the random

variable representing the number of non-defective

test booklets

Answer 1

There are $2^3=8$ possible outcomes

$DDD, DDN, DND, DNN,$ $NDD, NDN, NND, NNN$

Let $X$ be the random variable representing the number of non-defective

test booklets. Then

$$\begin{matrix} X & f \\ 0 & 1 \\ 1 & 3 \\ 2 & 3 \\ 3 & 1 \\ \end{matrix}$$

$$\def\arraystretch{1.5} \begin{array}{c:c} x & 0 & 1 & 2 & 3 \\ \hdashline p(x) & 1/8 & 3/8 & 3/8 & 1/8 \end{array}$$