Exploring the Normal Distribution and Its Key Percentages

What is the mean symbol in a normal distribution?

• Sigma

• Beta

• Alpha

• Mu

According to the 68-95-99.7 rule, what percentage of observations fall within one standard deviation of the mean?

• 95%

• 50%

• 99.7%

• 68%

What is the mean IQ score in the given example?

• 115

• 100

• 130

• 85

What percentage of people have IQ scores above 100?

• 50%

• 95%

• 68%

• 99.7%

What is the standard deviation of the IQ scores in the example?

• 25

• 15

• 20

• 10

What percentage of people have IQ scores above 145?

• 2.5%

• 16%

• 0.15%

• 5%

How many standard deviations away from the mean is an IQ score of 145?

• 1

• 2

• 3

• 4

What percentage of people have IQ scores below 85?

• 5%

• 0.15%

• 16%

• 2.5%

How many standard deviations away from the mean is an IQ score of 85?

• 4

• 3

• 2

• 1

If the mean IQ score is 100 and the standard deviation is 15, what is the IQ score at two standard deviations below the mean?

• 70

• 115

• 85

• 55