Question

If a die is thrown at random, then the expectation of the number on it is ______.

पर्याय

• 2.4

• 3.3

• 2.1

• 3.5

Answer 1

If a die is thrown at random, then the expectation of the number on it is 3.5.

Explanation:

A die is thrown

Random variable X = 1, 2, 3, 4, 5, 6

X	1	2	3	4	5	6
P(X)	`1/6`	`1/6`	`1/6`	`1/6`	`1/6`	`1/6`

E(X) = ∑ P(X) (X)

`= 1 xx 1/6 + 2 xx 1/6 + 3 xx 1/6 + 4 xx 1/6 + 5 xx 1/6 + 6 xx 1/6`

`= 1/6 (1 + 2 + 3 + 4 + 5 + 6)`

`= 1/6 xx 21 = 7/2 = 3.5`