Question

A fair coin is tossed till a head appears for the first time,. The probability that the number of required tosses is odd will be____

• A. 0.67

Answer 1

The correct option is A 0.67
$P\left(E\right)$=Probability of head appearing in odd number of tosses
$=P\left(H\right)+P\left(TTH\right)+......$

$=\frac{1}{2}+\left(\frac{1}{2}{)}^2\right(\frac{1}{2})+.....$

$=\frac{\frac{1}{2}}{1-\frac{1}{4}}=\frac{2}{3}=0.67$