The Normal Distribution

Question 0

Properties of the normal distribution curve

Answer 0

Bell-shaped and symmetric
Has an infinite base
Far out in the tails, the curve drops proportionally at an ever-increasing rate
The mean and medium are both at the center

Question 1

Normal distributions

Answer 1

Describe the results of sampling procedures
Are not always symmetric (unimodal distributions are normal)
Can be viewed as a limiting case of the binomial based on the law of large numbers

Question 2

Points of inflection

Answer 2

Points on each side where the slope is the steepest

The distance from the mean to either point is precisely equal to one standard deviation

Question 3

Z score equation

Answer 3

Z= (x-μ)/σ

Question 4

Ninety percent of values on a normal distribution curve are between z-scores:

Answer 4

-1.645 and +1.645

Question 5

Ninety five percent of values on a normal distribution curve are between z-scores:

Answer 5

-1.96 and +1.96

Question 6

Ninety nine percent of values on a normal distribution curve are between z-scores:

Answer 6

-2.576 and +2.576

Question 7

When is it not possible to use the normal model to approximate the binomial model

Answer 7

When n is small

Question 8

____________ is useful in gauging whether a given distribution of data is approximately normal

Answer 8

The normal probability plot

If the plot is nearly straight, the data is nearly normal