Answer:
[tex]\frac{3}{10}[/tex]
Step-by-step explanation:
The multiplies of 3 from 1-20 are:
3, 6, 9, 12, 15, 18
Since there are [tex]20-1+1=20[/tex] numbers from 1-20 inclusive, the probability that a ball is a multiple of 3 is [tex]\frac{6}{20}=\boxed{\frac{3}{10}}[/tex]
