Question

If X denotes the number of ones in five consecutive throws of a dice, then P(X = 4) is ______ 

Options

• `5/7776`

• `1/7776`

• 1

• `25/7776`

Answer 1

If X denotes the number of ones in five consecutive throws of a dice, then P(X = 4) is `underline(25/7776)`.

Explanation:

The probability of getting a 'one' in one throw is p = `1/6`

∴ q = `1 - 1/6 = 5/6`

Also, n = 5

∴ Required probability = P (X = 4)

= `""^5"C"_4(1/6)^4 . (5/6)^1 = 25/7776`