Question

The probability of getting a "head" in a single toss of a biased coin is 0.3. The coin is tossed repeatedly till a "head" is obtained. If the tosses are independent, then the probability of getting "head" for the first time in the fifth toss is .

• A. 0.072

Answer 1

The correct option is A 0.072

Probability of getting head = 0.3
$\therefore$ Probability of getting tail = 0.7

The head has to appear at fifth toss
So favouarble event is TTTTH

$\therefore P=\left(0.7{)}^4\right(0.3)=0.072$