Probability
Probability is the likelihood of something happening in the future.
It is expressed as a number between zero (can never happen) to 1
(will always happen). It can be expressed as a
fraction, a
decimal, or a
percent.
Here is a table of typical probabilities:
EVENT 
Probability 
as a fraction 
as a decimal 
as a percent 
The sun rises in the morning  1  1.0  100% 
A flipped coins turns up 'heads'  1/2  0.5  50% 
A card drawn out of a deck is a club  1/4  0.25  25% 
A card drawn out of a deck is a spade, heart, or diamond 
3/4  0.75  75% 
A kid flies by flapping her arms  0  0.  0% 
To learn more about probability, see the probability notes.
Here are a couple of problems for you:
 What is the probability of a birthday being on a Tuesday? _____
 What is the probability of drawing a red card out of a standard deck of 52 cards? _____
