Question:
If you have a collection of 6 pairs of white socks and 3 pairs of black socks. What is the probability that a pair you pick without looking is
(i) white?
(ii) black?
Solution:
Number of pairs of white socks $=6$
Number of pairs of black socks $=3$
Total number of pairs of socks $=6+3=9$
$\therefore$ Number of possible outcomes $=9$
(i) Let $A$ be the event of getting a pair of white socks.
$\therefore \mathrm{P}(\mathrm{A})=\frac{6}{9}=\frac{2}{3}$
(ii) Let $\mathrm{B}$ be the event of getting a pair of black socks.
$\therefore \mathrm{P}(\mathrm{B})=\frac{3}{9}=\frac{1}{3}$