Identify everyday events where one cannot happen if the other happens (ACMSP093)

Identify events where the chance of one will not be affected by the occurrence of the other (ACMSP094)

LO: To describe complementary and non-complementary events.

  • The probability scale ranges from 0 to 1.
  • That complementary and non-complementary events exist


  • That events can be complementary and non-complementary


  • I can identify complementary and non-complementary events.

Probability of Events

Probabilities of events can be described in a range of 0 to 1.

The probability of an event occurring can never be less than 0.

A probability of 0 means that the event is impossible to occur.

The probability of an event occurring can never be more than 1.

A probability of 1 means that the event is certain to occur.

Complementary Events

Complementary events are events that are opposite of each other and both can’t occur at the same time.
Complementary events can also be called mutually exclusive events.

For example, you can’t have a sunny day at the same time as having a rainy and cloudy day.

I also can’t roll a 1 on a die at the same time rolling a 6.

I also can’t win and lose at the same time. It has to be one option or the other.

Non-complementary events are events that won’t be affected by another event.

Non-complementary events can also be called independent events.

For example, I can roll a 6 on the dice and it won’t affect whether I flip a heads on a coin.

I can also get a Big Mac and choose whatever drink I want with it.

Complementary Events Videos