Events A and B are mutually exclusive. Suppose event A occurs with probability $0.19$ and event B occurs with probability $0.72$. If A does not occur, what is the probability that B does not occur? Round your answer to at least two decimal places.

My answer is $0.09/0.81=0.11$

Is my answer correct?

  • 2
    $\begingroup$ I don't understand the down vote. The OP stated his question clearly and showed his work. What more do you want? $\endgroup$ – saulspatz Apr 10 '18 at 6:17
  • $\begingroup$ Looks right to me. $\endgroup$ – saulspatz Apr 10 '18 at 6:19
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    $\begingroup$ Well, indeed, while Jake didn't show all the work, the numbers are certainly correct. It's not too bad as questions go. (Better than many we see.) $\endgroup$ – Graham Kemp Apr 10 '18 at 6:26

Yes.   But you really should show your work instead of just magic numbers. $$\begin{split}\mathsf P(B'\mid A')&=\dfrac{\mathsf P(B'\cap A')}{\mathsf P(A')}\\[2ex] &=\dfrac{1-\mathsf P(B)-\mathsf P(A)\require{cancel}\cancelto 0{+~\mathsf P(A\cap B)}}{1-\mathsf P(A)}\\[2ex] &= \dfrac{0.09}{0.81}\end{split}$$


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