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The '''probability''' of an event is typically expressed as the percentage of ways it might happen, out of a number of possible events. The chance of a tossed coin coming up heads is 50%, because there is 1 way it can happen, out of 2 possible ways. 1 / 2 = 0.5 or 50 percent.

The '''probability''' of an event is a number between 0 (representing impossibility), and 1 (representing certainty) and may be expressed as a simple fraction, decimal fraction or percentage. When there is a finite number of equally likely outcomes then the probability of an event is given by <math>\frac{\mbox{number of favourable outcomes}}{\mbox{number of possible outcomes}}</math>.

 

For example, The probability of a tossed fair coin coming up heads is &frac12; = 0.5 = 50% because there is one favourable outcome (heads) out of 2 possible outcomes (heads and tails).

With a standard deck of 52 [[playing card]]s, there are 13 cards in each suit: spades, hearts, clubs and diamonds. After you shuffle the cards thoroughly, what is the probability that the top card on the deck is a heart? 13 / 52 = 1 / 4 = 0.25 or 25 percent.

With a standard deck of 52 [[playing card]]s, there are 13 cards in each suit: spades, hearts, clubs and diamonds. After you shuffle the cards thoroughly, what is the probability that the top card on the deck is a heart? 13 / 52 = 1 / 4 = 0.25 or 25 percent.

==See also==

==See also==