Normal Distribution & Empirical Rule

Front

What is a normal distribution?

Back

A normal distribution is a probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean.

Front

What is the shape of a normal distribution curve?

Back

The shape of a normal distribution curve is called a bell curve.

Front

What is the Empirical Rule?

Back

The Empirical Rule states that for a normal distribution, approximately 68% of the data falls within one standard deviation of the mean, about 95% falls within two standard deviations, and about 99.7% falls within three standard deviations.

Front

What percentage of data falls within one standard deviation in a normal distribution?

Back

Approximately 68%.

Front

What percentage of data falls within two standard deviations in a normal distribution?

Back

Approximately 95%.

Front

What percentage of data falls within three standard deviations in a normal distribution?

Back

Approximately 99.7%.

Front

What is a disadvantage of the Empirical Rule?

Back

The data has to be approximately normal.

Front

If the average score of a test is 20.8 with a standard deviation of 3.9, what percent of students scored above the average?

Back

50%.

Front

If the average hourly wage for registered nurses is $32.75 with a standard deviation of $4.25, what percent of nurses make between $20 and $45.50?

Back

99.7%.

Front

What is the mean in a normal distribution?

Back

The mean is the average value of the data set, where the highest point of the bell curve occurs.