Question – One card is drawn from a deck of 52 cards. Each card is equally likely to be drawn. Find the probability that card drawn is either black or queen.
In this question we are going to use a simple formula
P(AB) = A ∪ B ∩ AB
Don’t be confused with the formula. Give a look to this diagram
In a deck of cards there are 26 black cards and 4 queens. But 2 black cards are queen. These cards are part of grey and brown circles in above diagram. As pink region is added twice, we need to deduct it once.
So the solution is 26 + 4 – 2 = 28
Probability (AB) = 28/52 = 7/13