CAIE S1 2019 June — Question 6

Exam BoardCAIE
ModuleS1 (Statistics 1)
Year2019
SessionJune
TopicDiscrete Probability Distributions
TypeExpected profit or cost problem

6 At a funfair, Amy pays \(
) 1$ for two attempts to make a bell ring by shooting at it with a water pistol.
  • If she makes the bell ring on her first attempt, she receives \(
    ) 3\( and stops playing. This means that overall she has gained \)\\( 2\).
  • If she makes the bell ring on her second attempt, she receives \(
    ) 1.50\( and stops playing. This means that overall she has gained \)\\( 0.50\).
  • If she does not make the bell ring in the two attempts, she has lost her original \(
    ) 1$.
The probability that Amy makes the bell ring on any attempt is 0.2 , independently of other attempts.
  1. Show that the probability that Amy loses her original \(
    ) 1$ is 0.64 .
  2. Complete the probability distribution table for the amount that Amy gains.
    Amy's gain (\$)
    Probability0.64
  3. Calculate Amy's expected gain.