ANSWER:
100%
STEP-BY-STEP EXPLANATION:
The first thing is to extract the sample spaces of the events, just like this:
A (even number) = {2, 4, 6, 8, 10, 12, 14}
B (multiple of 4) = {4, 8, 12}
A n B = {4, 8, 12}
Now, we calculate the probability of each case
[tex]\begin{gathered} P(A)=\frac{7}{15} \\ P(B)=\frac{3}{15}=\frac{1}{3} \\ P(A\cap B)=\frac{3}{15}=\frac{1}{3} \end{gathered}[/tex]We have that the probability P (A | B) is calculated as follows:
[tex]\begin{gathered} P(A|B)=\frac{P(A\cap B)}{P(B)} \\ \text{ replacing} \\ P(A|B)=\frac{\frac{1}{3}}{\frac{1}{3}}=1=100\text{\%} \end{gathered}[/tex]The probability is 100% since every multiple of 4 is even.