Answer
$P(cancer~|~25~to~34)=\frac{0.0015}{0.0171}\approx0.00877$
Work Step by Step
$P(25~to~34)=1.71$% $=0.0171$
$P(25~to~34~and~cancer)=0.15$% $=0.0015$
Using the Conditional Probability Rule (see page 288):
$P(cancer~|~25~to~34)=\frac{P(25~to~34~and~cancer)}{P(25~to~34)}=\frac{0.0015}{0.0171}\approx0.00877$
