Question 8: Drug Test

alexalex
edited June 11 in Student Questions

Hey all,
I'm having trouble with the last 3 questions of this problem. It's structured similarly to the problem we did in class, but in that example we were given the likelihood of someone in the population having the disease. In this case we are asked to solve %P(D)%, but I feel like there is not enough info. What am I missing?

In other words, I think the equation we're working with is:
%P(T|D)=(P(T and D))/(P(D)) %
But we are only given values for %P(T|D)%, %P(T|D^c)% and %P(T)%.

mark

Comments

  • markmark
    edited June 12

    I suggest that you start with something that you know already - like $P(T)$. Expand $T$ out into $$T = (T \cap D) \cup (T \cap D^c)$$ and see if you can find a $P(D)$ in there that you can solve for.

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