Question:
In a lottery, there are 10 prizes and 20 blanks. A ticket is chosen at random. What is the probability of getting a prize?
Solution:
Total number of tickets $=10+20=30$
Number of prize tickets $=10$
$\therefore \mathrm{P}_{\text {(getting a prize) }}=\frac{10}{30}=\frac{1}{3}$