Question 1162301
<br>
"OR" means ADD the probabilities.<br>
In this example you need to be careful, because "three" and "club" overlap.<br>
P(three OR club) = P((three) OR (club that is not a three)) = 4/52 + 12/52 = 16/52 = 4/13.<br>
Of course, you could calculate the probability as<br>
P(three OR club) = P((club) OR (three that is not a club)) = 13/52 + 3/52 = 16/52 = 4/13.<br>
Finally, a technique that is often required for more complicated problems is to calculate the probability that it is a club or that it is a three and then subtract the probability that it is both -- because you have counted that probability twice.<br>
P(three OR club) = P(three) + P(club) - P(three of clubs) = 4/52 + 13/52 = 1/52 = 16/52 = 4/13<br>