**7.2 Probability of the Complement of an Event**

**1.**The

**complement**of an event

*A*is the set of all the outcomes in the sample space that are not included in the outcomes of event

*A*.

**2.**The probability of the complement of event

*A*is:

$\overline{)\text{}P\left(A\text{'}\right)=1-P\left(A\right)\text{}}$

**Example:**

A
number is chosen at random from a set of whole number from 1 to 40. Calculate the
probability that the chosen number is

**not**a perfect square.

*Solution:*
Let

*A*= Event of choosing a perfect square.

*A’*= Event that the number is not a perfect square.

*A*= {1, 4, 9, 16, 25, 36}

*n*(

*A*) = 6