Standard Deviation (50 points)
Dr. Cwetna recorded all of the grades on a unit test on the chart below.

1. What is the mean and standard deviation of the distribution of individual grades? (30
points)
x=

o=

2. In your own words, explain HOW to find the standard deviation of this data set. (20
points)

3. What does the standard deviation tell you about this data? (20 points)

4. Identify the following and label the dot-plot above (3 points each)
u+-1o= and

u+-20= and

u+-3o= and

Find the percentage of test scores within each range listed above.
5. (4 points) Does the data indicate a normal distribution?

6. (8 points) Explain why or why not?