3.3 Normal distribution: areas to the left and right of x

The arrow in the graph below points to the area to the left of $x$ . This area is represented by the probability $P(X< x)$ . Normal tables, computers, and calculators provide or calculate the probability $P(X< x)$ .

The area to the right is then $P(X> x)=1-P(X< x)$ .

Remember, $P(X< x)=$ Area to the left of the vertical line through $x$ .

$P(X> x)=1-P(X< x)=$ . Area to the right of the vertical line through $x$

$P(X< x)$ is the same as $P(X\le x)$ and $P(X> x)$ is the same as $P(X\ge x)$ for continuous distributions.