The probabilities are as follows:
- Probability of being a teenager: P(teenager)=0.375
- Probability of being at least 20 years old: P(at least 20)=0.625
- Probability of being 30 or older: P(at least 30)=0.125
Thus, the final answers are:
P(teenager)=0.375,P(at least 20)=0.625,P(at least 30)=0.125