Question

For the following probability distribution:

X	1	2	3	4
P(X)	`1/10`	`3/10`	`3/10`	`2/5`

E(X²) is equal to ______.

Options

• 3

• 5

• 7

• 10

Answer 1

For the following probability distribution:

X	1	2	3	4
P(X)	`1/10`	`3/10`	`3/10`	`2/5`

E(X²) is equal to 10.

Explanation:

We know that

E(X²) = `sum_("i" = 1)^"n" "P"_"i""X"_"i"^2`

= `1 xx 1/10 + 4 xx 1/5 + 9 xx 3/10 + 16 xx 2/5`

= `1/10 + 4/5 + 27/10 + 32/5`

= `28/10 + 36/5`

= `100/10`

= 10