CAIE S1 2021 November — Question 1

Exam BoardCAIE
ModuleS1 (Statistics 1)
Year2021
SessionNovember
TopicGeometric Distribution
TypeCompound event with two dice/coins

1 Two fair coins are thrown at the same time. The random variable \(X\) is the number of throws of the two coins required to obtain two tails at the same time.
  1. Find the probability that two tails are obtained for the first time on the 7th throw.
  2. Find the probability that it takes more than 9 throws to obtain two tails for the first time.