Q37 / 60 · JEE Advanced 2009 (Paper 1) · Mathematics

Paragraph: A fair die is tossed repeatedly until a six is obtained. Let $X$ denotes the number of tosses required.Question: The probability that $X \geq 3$ equals

  • A
    $\frac{125}{216}$
  • Correct answer
    B
    $\frac{25}{36}$
  • C
    $\frac{5}{36}$
  • D
    $\frac{25}{216}$

Solution

$P(X \geq 3)=\frac{5}{6} \cdot \frac{5}{6} \cdot 1=\frac{25}{36}$

Hence, the correct answer is option: 'B'.

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