How do you solve questions concerning probability?

To solve questions where you need to find the probability
of any event taking place, you first need to determine two
values:

1. The number of ways in which the event can take
place (a)

2. The total number of events that are possible
(b)

Using these values, the probability of the event taking
place is given by the value of a/b.

The value of the
probability of anything happening or not happening always lies in the set [0, 1]. No
event can have a probability less than 0 or more than 1. The probability of an event not
taking place is equal to 1 - the probability of the event taking
place.

Given the probability of two mutually exclusive
events a and b taking place as P(a) and P(b), the probability that both take place is
P(a)*P(b) and the probability that either of them takes place is P(a) +
P(b).