Question

The table below shows one doctor's patients who got the flu and whether or not they took avitamin each day.Took VitaminDid not take vitaminTotalsGot the flu253055Did not get the fluWhat is P(took a vitamin | did not get the flu)?351045Totals6040100

Answer 1

Let's set A=took vitamin and B= did not get the flu.

The P(took vitamin | did not get the flu) is given by:

$P(A|B)=\frac{P(A\cap B)}{P(B)}$

In the table of values, we can observe that:

By replacing these values in the formula, the result we obtain is:

$\begin{gathered} P(A|B)=\frac{35}{45} \\ \\ Simplify \\ P(A|B)=\frac{7}{9} \end{gathered}$

Therefore, P(took vitamin | did not get the flu)=7/9