In a lottery, there are 10 prizes and 20 blanks. What is the probability of getting a prize?

In a lottery, there are 5 prizes and 20 blanks. The probability of getting a prize is

In a lottery, there are 10 prizes and 25 blanks. Find the probability of getting a prize.

In a lottery, there are 8 prizes and 16 blanks. What is the probability of getting a prize?
(a) $\frac{1}{2}$ (b) $\frac{1}{3}$ (c) $\frac{2}{3}$ (d) None of these