CAIE S1 2022 June — Question 6

Exam BoardCAIE
ModuleS1 (Statistics 1)
Year2022
SessionJune
TopicConditional Probability
TypeConditional with three or more stages

6 Janice is playing a computer game. She has to complete level 1 and level 2 to finish the game. She is allowed at most two attempts at any level.
  • For level 1 , the probability that Janice completes it at the first attempt is 0.6 . If she fails at her first attempt, the probability that she completes it at the second attempt is 0.3 .
  • If Janice completes level 1, she immediately moves on to level 2.
  • For level 2, the probability that Janice completes it at the first attempt is 0.4 . If she fails at her first attempt, the probability that she completes it at the second attempt is 0.2 .
    1. Show that the probability that Janice moves on to level 2 is 0.72 .
    2. Find the probability that Janice finishes the game.
    3. Find the probability that Janice fails exactly one attempt, given that she finishes the game.
If you use the following lined page to complete the answer(s) to any question(s), the question number(s) must be clearly shown.