A city has people with Blood Types as follows: Type O 45%
Type A 40%
Type B 11%
Type AB 4% Two persons are selected at random from the city.
Find the probability that at least one person is of Blood Type O. Answer ___

1. Find the probability that a selected person is not of Blood Type O.

$P(\text{not O})=100\%-45\%=55\%=0.55$

2. Use the complement of 'at least one Type O' for two selections.

$P(\text{at least one O})=1-P(\text{no O})$

$=1-(0.55)(0.55)$

$=1-0.3025$

$=0.6975$