Question

If three dices are thrown then the probability that the sum of the numbers on their uppermost faces to be atleast 5 is ______.

Options

• `1/53`

• `53/54`

• `1/54`

• `52/53`

Answer 1

If three dices are thrown then the probability that the sum of the numbers on their uppermost faces to be atleast 5 is `underline(53/54)`.

Explanation:

If there dice are drawn, then n(s) = 6³ = 216

Let Ethe sum of the number on their uppermost faces are less than 5 as follows

(1, 1, 1), (1, 1, 2), (1, 2, 1), (2, 1, 1)

∴ n(E) = 4

Now, probability that the sum of the numbers on their uppermost faces to be atleast 5

= 1 - P(E₂)

= `1 - 4/216`

`= 1 - 1/54 = 53/54`