Question

. Find the probability that the coin turns up heads for the first time on the tenth, eleventh, or twelfth toss.

Answer 1

0.001709

Explanation:

The probability of getting 9 tails then 1 head is:

(½)⁹ (½)¹ = (½)¹⁰

The probability of getting 10 tails then 1 head is:

(½)¹⁰ (½)¹ = (½)¹¹

The probability of getting 11 tails then 1 head is:

(½)¹¹ (½)¹ = (½)¹²

The total probability is:

(½)¹⁰ + (½)¹¹ + (½)¹²

0.001709