excans:9b011a2d0c: Difference between revisions

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<math display = "block">
<math display = "block">
\begin{align*}
\begin{align*}
\operatorname{P}[( A ∪ B ∪ C ) | A^c] &= \frac{\operatorname{P}[( A ∪ B ∪ C )]}{\operatorname{P}[A^c]} \\
\operatorname{P}[( A ∪ B ∪ C )^c | A^c] &= \frac{\operatorname{P}[( A ∪ B ∪ C )^c]}{\operatorname{P}[A^c]} \\
&= \frac{1− \operatorname{P}[ A ∪ B ∪ C]}{1-\operatorname{P}[A]} \\
&= \frac{1− \operatorname{P}[ A ∪ B ∪ C]}{1-\operatorname{P}[A]} \\
&= \frac{1 − 3 ( 0.10 ) − 3 ( 0.12 ) − 0.06}{1 − 0.10 − 2 ( 0.12 ) − 0.06} \\
&= \frac{1 − 3 ( 0.10 ) − 3 ( 0.12 ) − 0.06}{1 − 0.10 − 2 ( 0.12 ) − 0.06} \\

Latest revision as of 22:19, 1 July 2024

Solution: C

Let x be the probability of having all three risk factors.

[[math]] \frac{1}{3} = \operatorname{P}[A \cap B \cap C | A \cap B ] = \frac{\operatorname{P}[A \cap B \cap C]}{\operatorname{P}[A \cap B]} [[/math]]

It follows that

[[math]] \begin{align*} x = \frac{1}{3}(x + 0.12 ) &= \frac{1}{3}x + 0.04 \\ \frac{2}{3}x &= 0.04 \\ x &= 0.06. \end{align*} [[/math]]

Now we want to find

[[math]] \begin{align*} \operatorname{P}[( A ∪ B ∪ C )^c | A^c] &= \frac{\operatorname{P}[( A ∪ B ∪ C )^c]}{\operatorname{P}[A^c]} \\ &= \frac{1− \operatorname{P}[ A ∪ B ∪ C]}{1-\operatorname{P}[A]} \\ &= \frac{1 − 3 ( 0.10 ) − 3 ( 0.12 ) − 0.06}{1 − 0.10 − 2 ( 0.12 ) − 0.06} \\ &= \frac{0.28}{0.60} = 0.467 \end{align*} [[/math]]

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