Chapter 6: The Normal Distribution
© STAT 110 Team 2018
1. Select the
“Data” tab.
2. Click on MegaStat.
3. Choose probability, then click on the field
“Normal Distribution”
3. Choose
“Probability”, then click on the field
“Normal Distribution”
Finding the Area Under the Normal Distribution Curve
Case 1a: To the left of any ±Z value.
Case 1b: To the left of any X value.
Case 2a: To the right of any ±Z value.
Case 2b: To the right of any X value.
Case 3a: Between two Z values.
Case 3b: Between two X values.
Example 6 – 1 (Case 1a)
Find the area to the left of z = 2.09.
Add the required value here. Then
click OK.
Add the required z value here. Then
click OK.
Example 6 – 1 (Case 1a) (cont.)
Sol. Area = 0.9817
Example 6 – 6 (Case 1b)
Find the area to the left of X = 5.4, such that µ = 5.2 and σ = 0.3.
2. Add the value of the mean (µ) here.
1. Add the required x value here.
3. Add the value of the standard deviation (σ) here.
Then click OK.
3. Add the value of the standard deviation (σ) here.
Then click OK.
Example 6 – 6 (Case 1b) (cont.)
Sol. Area = 0.7475
Important Note:
In the textbook, the area was calculated to be 0.7486. The
difference between the results is because the author of the book calculated the area based on z = 0.67, while MegaStat
calculated the area based on z =
0.666666666666667.
Example 6 – 2 (Case 2a)
Find the area to the right of z = -1.14.
1. Add the required value here.
2. Change the option to “upper”,
then OK.
2. Change the option to “upper”,
then OK.
Example 6 – 2 (Case 2a) (cont.)
Sol. Area = 0.8729
Example 6 – 7b (Case 2b)
Find the area to the right of X = 30.2, such that µ = 28 and σ = 2.
2. Add the value of the mean (µ) here.
1. Add the required x value here.
3. Add the value of the standard deviation (σ) here.
4. Change the option to “upper”,
then OK.
4. Change the option to “upper”,
then OK.
Example 6 – 7b (Case 2b) (cont.)
