## Algebra 2 (1st Edition)

$\frac{7}{8}$
We know that $P(\text{A and B})=P(A)P(B|A)$, thus $P(B|A)=\frac{P(\text{A and B})}{P(A)}=\frac{\frac{7}{20}}{\frac{8}{20}}=\frac{7}{8}$ Out of the group, there are 8 prime numbers and 7 even numbers.