Question

For the following probability distribution:

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

$E(X)$ is equal to

• A. $0$
• B. $-1$
• C. $-2$
• D. $-1.8$

Answer 1

Answer: (D)

$E\left(X\right)=\Sigma XP\left(X\right)$
$=\left(-4\right)\times 0.1+\left(-3\right)\times 0.2+\left(-2\right)\times 0.3+\left(-1\right)\times 0.2+0\times 0.2$
$=-0.4-0.6-0.6-0.2=-1.8$