Ch 3; Normal Distributions

Question 1

Density Curves

Answer 1

A curve that is always above the horizontal axis & has area exactly 1 underneath it

Question 2

What Does Density Curve Show

Answer 2

Overall pattern of a distribution

Question 3

Mean (Density Curve)

Answer 3

The balance point at which the curve would balance if made of solid material

Question 4

Median (Density Curve)

Answer 4

The point that divides the area under the curve in half.

Question 5

When is A Density Curve Best Used

Answer 5

If distribution is basically symmetrical.

Question 6

Mean & Median for a Symmetrical Curve

Answer 6

Equal

Question 7

Mean & Median for a Skewed Curve

Answer 7

Mean in direction of tail.

Question 8

Normal Curve Shape

Answer 8

Symmetric, single peaked, bell shaped

Question 9

What can a Normal be Completely Described By

Answer 9

Mean (μ) & Standard Deviation (σ)

Question 10

What is the Proper Notation for a Normal Distribution

Answer 10

N(μ,σ)

Question 11

What happens when you Change μ Without Changing σ

Answer 11

Curve moves along horizontal axis without changing variability

Question 12

What happens when you Change σ

Answer 12

Controls the variability of the normal curve. (Smaller σ = narrower curve)

Question 13

How to Find Standard Deviation in Normal Curve

Answer 13

Point at which curvature changes

Question 14

Describe the 68-95-99.7

Answer 14

68% of observations fall w/in σ of the mean μ
95% of observations fall w/in 2σ of the mean μ
99.7% of observations fall w/in 3σ of the mean μ

Question 15

Standardized Value Equation (z)

Answer 15

Z = x - μ / σ

Question 16

Describe the Characteristics of a Standard Normal Distribution

Answer 16

N(0,1) w/ mean 0 & standard deviation 1

Question 17

Cumulative Proportion

Answer 17

For value x in a distribution is the proportion of observations in the distribution that are less than or equal to x