Download Finding Areas under the Standard Normal Curve Example 1

Finding Areas under the Standard Normal Curve
Example 1: Determine the area under the standard normal curve that lies to
the left of z = 1.35
1.35
Z
Press `v to access the
probability distribution menu
“DISTR”.
Select 2:normalcdf(
Normalcdf computes the normal
distribution probability between an
upper and lower bound for a
specified mean and standard
deviation.
Press e.
The syntax is (lowerbound,
upperbound, mean, std deviation).
When there is no lowerbound, enter
-1E99.
When there is no upperbound, enter
1E99.
(Press `, for scientific notation
E)
We are not given a lowerbound, so
enter -1E99.
The upperbound is 1.35.
Since this is a standard normal curve,
the mean is 0 and the standard
deviation is 1.
Thus, the area to the left of 1.35 is
.9115
Example 2: Determine the area under the standard normal curve that lies to
the right of z =2.23
2.23
Z
Press `v to access the
probability distribution menu
“DISTR”.
Select 2:normalcdf(
Press e.
The lowerbound is 2.23.
We are not given an upperbound so
enter 1E99.
Since this is a standard normal curve,
the mean is 0 and the standard
deviation is 1.
Thus, the area to the right of 2.23 is
0.0129
Example 3: Determine the area under the standard normal curve that lies
between z = -1.35 and z = 2.01
Press `v to access the
probability distribution menu
“DISTR”.
Select 2:normalcdf(
Press e.
The lowerbound is -1.35.
The upperbound is 2.01.
Since this is a standard normal curve,
the mean is 0 and the standard
deviation is 1.
Thus, the area between -1.35 and 2.01
is 0.8893
Dr JM Raines © 2011