Question

Mark the correct alternative in the following question:

For the following probability distribution:

X:	−4	−3	−2	−1	0
P(X):	0.1	0.2	0.3	0.2	0.2

The value of E(X) is

(a) 0 (b) −1 (c) −2 (d) −1.8

Answer 1

The probability distribution of X is given below:

X:	−4	−3	−2	−1	0
P(X):	0.1	0.2	0.3	0.2	0.2

$$\begin{gathered} \mathrm{E}\left(X\right)=\left(-4\right)\times 0.1+\left(-3\right)\times 0.2+\left(-2\right)\times 0.3+\left(-1\right)\times 0.2+0\times 0.2 \\ =-0.4-0.6-0.6-0.2 \\ =-1.8 \end{gathered}$$

Hence, the correct alternative is option (d).