Probability: A fair die is tossed until six is obtained on it. Let X be the… | JEE Main 2021 | Yukti Vault

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JEE Main 2021 (Online) 26th August Evening ShiftQuestion 1

A fair die is tossed until six is obtained on it. Let $X$ be the number of required tosses, then the conditional probability $P(X\ge5\mid X>2)$ is :

Probability

$\frac{11}{36}$$\frac{25}{36}$✓ Correct answer$\frac{5}{6}$$\frac{125}{216}$

Solution

$P(X>n)=(5/6)^n$. $P(X\ge5\mid X>2)=\frac{P(X>4)}{P(X>2)}=(5/6)^2=\frac{25}{36}$. Option B.

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