Normal Distribution

Question 1

What is the notation for normal distribution?

Answer 1

N ( μ , σ )
N= normally distributed
μ = mean/median
σ = sigma (standard deviation)

Question 2

Where does all the data fall on a normal distribution curve?

Answer 2

Within 3 standard deviations

Question 3

What shape is a normal distribution curve?

Answer 3

A bell curve

Question 4

What are some basic properties of normal distribution?

Answer 4

• symmetric about the mean
• the mean = the mode = the median
• the mean divides the data in half
• defined by mean and standard deviation
• the curve is unimodal (one peak)
• the curve approaches, but never touches the x axis
• total area under the curve = 1

Question 5

What are some examples of normal distribution?

Answer 5

• height
• foot size
• weight
• blood pressure
• IQ
• life span
• test results

Question 6

What does the area under the bell curve represent?

Answer 6

100% of all the data

Question 7

What is the empirical rule?

Answer 7

• approximately 68% of the data will fall within one standard deviation
• approximately 95% of the data will fall within two standard deviations
• approximately 97.5% of the data will fall within three standard deviations