Question

Let a die rolled till 2 is obtained. The probability that 2 obtained on even numbered toss is equal to:

• A. $\frac {5}{11}$
• B. $\frac {5}{6}$
• C. $\frac {1}{11}$
• D. $\frac {6}{11}$

Answer 1

Answer: (A)

$\frac {5}{11}$

Answer 2

The correct option is (A) : $\frac {5}{11}$
P(2 obtained on even numbered toss) = k(let)
$P(2)=\frac{1}{6}$
$P(\overline2)=\frac{5}{6}$
$k=\frac{5}{6}\times\frac{1}{6}+(\frac{5}{6})^3\times\frac{1}{6}\times(\frac{5}{6})^5\times\frac{1}{6}+....$
$=\frac{\frac{5}{6}\times\frac{1}{6}}{1-(\frac{5}{6})^2}$
$=\frac{5}{11}$