The following formula can be used to find the probability of an outcomes where two events are equally likely:
If a bag contains 10 marbles, of which 1 is yellow, 3 is green, 4 is blue and 2 are red marbles. What is the probability of pulling a blue marble?
If the probability of an event occurring is p then the probability of an event not occurring is 1 – p
What would be the probability of not pulling out a blue marble?
The probability of pulling out a blue marble is 0.4
Therefore 1 – 0.4 = 0.6