How can we express probability?

Probability is how likely something is to happen, and we sometimes here it called chance. So, the probability of something happening means how likely it is to happen. It can be expressed in two main ways: 1) A probability scale. A probability scale looks like a number line, with 0 and 1 at either end. The 0 is labelled "Impossible", as there is 0 chance of it happening. The 1 is labelled "Certain", as it will definitly happen. [This is because 1 is the maximum value our probability can take, so all our probabilities must sum to 1]. Half way along the line is labelled "Even", which means there is an equal chance of the event either happening or not happening [think of tossing a two-sided coin!]. At a quarter is "Unlikely", and three quarters is "Likely". These are used to help position events when they are not impossible/certain, but not evens. 2) A Fraction or a Decimal. I'll demonstrate this by example. Let's think of an ordinary, fair 6-sided die [Are fair and unbiased the same?]. When I roll this die, the outcomes I could get are "1,2,3,4,5,6". The event which would have probability 1, which I could say is certain of happening, is that "I roll a number". Next I could ask "What fraction of the possible outcomes is greater than 3?", which would be 1/2, because the only outcomes greater than 3 are "4,5,6", which is half of the possible outcomes I could get. So, because probability is how likely something is to happen, I could say "The probability of rolling a number greater than 3 is 1/2". The definition of the probability of an event is in the form of a fraction, and it is given by: Probability of an event = (Number of successful outcomes)/(Total number of outcomes) [Can you see from the definition why our probabilities can't be bigger than 1? Hint: Can the number of successful outcomes be bigger than the total outcomes?]