# Copy of Normal Distribution Calculator

- Author:
- Dr Deepak Shah, rachelphillips

Seeing data in the Normal Distribution Curve
Use the Normal Distribution Calculator to complete these problems.
1. Fill in the blanks for the following properties of normal distributions:
a) The MEAN is located on the ___ of the Normal Curve.
b) In the PROBABILITY of: column, click on the BETWEEN box and change the values in the boxes that appear to -3 ≤ x ≤ 3.
What is the probability ____?
c) Now change the values in these BETWEEN boxes to -1 ≤ x ≤ 1.
What is the probability ____?
d) Now change the values in these BETWEEN boxes to 1 ≤ x ≤ 3.
What is the probability ____?
2. Fill in the blanks for the following properties of normal distributions:
a) About ___% of the area under the curve is within 1 standard deviation to the left of the mean. Change the numbers in the PROBABILITY of: BETWEEN boxes to -1 ≤ x ≤ 0.
b) About __% of the area under the curve is 2 and 3 standard deviations to the right of the mean. Change the numbers in the PROBABILITY of: BETWEEN boxes to 1 ≤ x ≤ 2.
c) About ___% of the area under the curve is within1 standard deviations from the mean. Change the numbers in the PROBABILITY of: BETWEEN boxes to -3 ≤ x ≤ -2.
d) How do you know the above values are true? (not because the calculator said so)
What is it about the Normal Curve that allows you to be certain?
3. A set of 360 data points are normally distributed with a mean of 180 and a standard deviation of 45.
a) What is the probability that a value will be between 90 and 270?
What information on the curve was used to find this probability?
b) What is the probability that a value will be below 180?
Why is this true?
c) What is the mean of this data?