## College Algebra (10th Edition)

We know that probability$=\frac{\text{number of favourable outcomes}}{\text{number of all outcomes}}.$ Let $X$ be the even numbers in $S$, thus $X=\{1,3,5,7,9\}$. Hence here probability$=\frac{|X|}{|S|}=\frac{5}{10}=0.5.$