Basic Probability Examples

If you draw a card from a standard deck of cards, what is the probability of drawing a face card?

There are 4 suits with 3 face cards each. This makes a total of 3 × 4 = 12 face cards out of 52 cards.

If you draw a card from a standard deck of cards, what is the probability of not drawing a spade?

There are 13 spades, so that means that there are 52 – 13 = 39 cards that are not spades.

If you roll two dice, what is the probability that the sum of the two is odd?

As we can see in the chart above, there are 18 combinations that result in an odd sum. There are still 36 different combinations, so: