Complementary events help us understand probability better, especially in Gymnasium Year 1 Mathematics.

So, what is a complementary event?

It includes all the possible outcomes that do not happen in a specific event.

If we have an event called $A$, its complementary event is written as $A'$.

Key Ideas:

• Probability of an Event: This tells us how likely it is for an event, $A$, to happen. We write it as $P(A)$.

• Probability of Complementary Events: To find the probability of the complementary event $A'$, we can use this simple formula:

  $P(A') = 1 - P(A)$

Example:

Let’s say the chance of it raining on a certain day is $P(A) = 0.3$.

To find the chance of it not raining (which is the complementary event), we calculate:

$P(A') = 1 - 0.3 = 0.7$

Understanding Better:

Using complementary events can make calculations easier and help us make better choices.

For example, in games, knowing the chances of winning or losing can be clearer when we use complementary probabilities.

This understanding helps students grasp probability concepts in a more natural way.