1. Probability of a single event
Wednesday, April 24, 2019
Probability of a single event
A Probability is a number between 0 and 1 and is always expressed as a fraction, decimal or percentage –usually a fraction  1
Impossible
Certainty
Even Chance
Less Likely
More Likely
The probability of me being king some day is impossible i.e. No chance  0
The probability that you will learn something from this powerpoint is certain  1
A probability is a value given to events which may arise out of an experiment based on equally likely outcomes

2. What is the probability of the coin landing heads up?
Example
A fair coin is tossed.
What is the probability of the coin landing heads up?
Possible outcomes: Head & Tails (2)
Number of heads = 1
P(Heads) =

3. Remember there is only one 4 on a fair die
Example
A fair die is thrown.
How many possible outcomes are there?
What is the probability of getting a 4?
a) Possible outcomes: 1, 2, 3, 4, 5, 6 Number of outcomes = 6
b) P(4) =
Remember there is only one 4 on a fair die

4. Example
A normal cubical die is thrown. Find the probability of obtaining a five or more?
Five or more means a 5 or a 6 (2 possible solutions)
P(5 or more ) =

5. A bag contains 3 red counters, 2 blue counters and 4 white counters.
Example
A bag contains 3 red counters, 2 blue counters and 4 white counters.
Obtain the probability of picking a red counter at random from the bag.
Total number of counters = = 9
Number of reds = 3
P(red) =

6. Example
A bag contains 24 counters. 4 are green, 11 are red, 7 are blue and the rest are white.
Find the probability that the first counter picked at random will be blue.
Find the probability that the first counter picked out of the bag is not red.
Find the probability that the first counter picked at random will be yellow.
P(Blue) =
P(not red) =
P(yellow) =