Normal Distribution and the Empirical Rule

Which interval shows 95% of the data given a mean of 15 and a standard deviation of 3? 

• 9 to 21

• 12 to 18

• 6 to 24

• 13 to 16

What percent of people within 3 standard deviations of the mean?

• 99.7

• 34

• 68

• 95

What percent of people within 2 standard deviations of the mean?

• 99.7

• 34

• 68

• 95

What percent of people within 1 standard deviation of the mean?

• 99.7

• 34

• 68

• 95

What percentage of the data is between 1 and 2 standard deviations

• 34%

• 50%

• 2.35%

• 13.5%

What percent of people are 3 standard deviations above the mean?

• .15

• 34

• 68

• 2.35

500 juniors at Central High School took the ACT last year. The scores were distributed normally with μ=24 and σ=4.

What percent of ACT scores are between 20 and 28?

• 34%

• 68%

• 81.5%

• 95%

2000 freshmen at State Univ. took a Biology test. The scores were distributed normally with μ=70 and σ=5.

What percent of scores are less than 70?

• 34%

• 50%

• 16%

• 84%

2000 freshmen at State Univ. took a Biology test. The scores were distributed normally with μ=70 and σ=5. What percent of scores are between 65 and 75?

• 34%

• 50%

• 68%

• 81.5%

The center of the curve represents what value of a data set?

• μ

• δ

• Σ

• Ζ