By Tomas Chlebecek

You select a card form a standard deck of 52 cards. Find the probability that the card is a 4 or an ace.

If the card is a 4, it cannot be an ace.

Use the Addition Rule to find the probability!

P(a or b) = P(a) + P (b) – P(a and b) If the events are mutually exclusive you may

simplify the rule into…P(a or b) = P(a) + P(b)

P(4 or Ace) = P(4) + P(Ace) = 4/52 + 4/52 = 8/52 = 2/13 = 0.154

As you can see…the Addition Rule helped me find the answer by adding the two Fractional Integers then simplifying the sum!

The probability that the card drawn is either a 4 or an Ace is 0.154 !!! Or 15.4%