CAIE S1 2023 June — Question 1

Exam BoardCAIE
ModuleS1 (Statistics 1)
Year2023
SessionJune
TopicGeometric Distribution
TypeCompound event with two dice/coins

1 Two fair coins are thrown at the same time repeatedly until a pair of heads is obtained. The number of throws taken is denoted by the random variable \(X\).
  1. State the value of \(\mathrm { E } ( X )\).
  2. Find the probability that exactly 5 throws are required to obtain a pair of heads.
  3. Find the probability that fewer than 7 throws are required to obtain a pair of heads.