CAIE S1 2024 November — Question 7

Exam BoardCAIE
ModuleS1 (Statistics 1)
Year2024
SessionNovember
TopicGeometric Distribution
TypeP(a ≤ X ≤ b) range probability

7 In a game,players attempt to score a goal by kicking a ball into a net.The probability that Leno scores a goal is 0.4 on any attempt,independently of all other attempts.The random variable \(X\) denotes the number of attempts that it takes Leno to score a goal.
  1. Find \(\mathrm { P } ( X = 5 )\) .
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  2. Find \(\mathrm { P } ( 3 \leqslant X \leqslant 7 )\) .
  3. Find the probability that Leno scores his second goal on or before his 5th attempt.
    \includegraphics[max width=\textwidth, alt={}, center]{aeb7b26e-6754-4c61-b71e-e8169c617b91-10_2715_33_106_2017}
    \includegraphics[max width=\textwidth, alt={}, center]{aeb7b26e-6754-4c61-b71e-e8169c617b91-11_2723_33_99_22} Leno has 75 attempts to score a goal.
  4. Use a suitable approximation to find the probability that Leno scores more than 28 goals but fewer than 35 goals.
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