Question

Mark the correct alternative in the following question:

For the following probability distribution:
 

X :	1	2	3	4
P(X) :	\[\frac{1}{10}\]	\[\frac{1}{5}\]	\[\frac{3}{10}\]	\[\frac{2}{5}\]

The value of E(X²) is

Options

• 3     

•  5   

•  7   

•  10

Answer 1

The probability distribution of X is given below:

X :	1	2	3	4
P(X) :	\[\frac{1}{10}\]	\[\frac{1}{5}\]	\[\frac{3}{10}\]	\[\frac{2}{5}\]

\[E\left( X^2 \right) = 1^2 \times \frac{1}{10} + 2^2 \times \frac{1}{5} + 3^2 \times \frac{3}{10} + 4^2 \times \frac{2}{5}\]
\[ = \frac{1}{10} + \frac{8}{10} + \frac{27}{10} + \frac{64}{10}\]
\[ = \frac{100}{10}\]
\[ = 10\]