Wamup What information can you get from the graph? Which had a more symmetrical distribution of scores?

2 Normal Distributions Lesson 14

REMEMBER your box plot LQUQ Middle 50% range

The Normal Distribution (Bell Curve) Average contents 50 But do they always contain exactly 50?

Definitions mean 50% above mean 50% below mean Standard Deviations are listed at the bottom – formal definition is: a statistical measure of the amount by which a set of values differs from the arithmetical mean, equal to the square root of the mean of the differences' squares Normal curves are also called bell curves. Normal curves are symmetrical. New York Regents Test Explanation

6 Percent of Values Within One Standard Deviations 68.26% of Cases + 1 Standard Deviation

7 Percent of Values Within Two Standard Deviations 95.44% of Cases + 2 Standard Deviations

8 Percent of Values Within Three Standard Deviations 99.72% of Cases + 3 Standard Deviations

9 Percent of Values Greater than -2 Standard Deviations

10 Percent of Values Greater than +2 Standard Deviations

IQ Normal Distribution Your Teacher? 1.What percentage of the population have IQs greater than 100? 2.What percentage of the population have IQs greater than 130? 3. What percentage of the population have IQs less than 85?

1.What is the maximum value of the curve? 2.What percentage of the curve is shaded? 3.What percentage of the curve is not shaded? 4.What is the minimum value? 5.Where is the mean located? 6.Where is the median located? 7.Where is the mode located?

Test Scores The distribution graph to the left shows the scores of a recent exam featuring 70 questions. The scale is marked for each standard deviation. 1.What is the mean score? 2.What is the standard deviation? 3.What percentage of the scores are above 52? 4.What percentage of the scores fall between 46 and 58? 5.What percentage of the scores fall above 64? Key:

Interactives The more trials you have, the closer it becomes to a normal curve.