z-scores

Front

What is a z-score?

Back

A z-score is a statistical measurement that describes a value's relationship to the mean of a group of values, expressed in terms of standard deviations from the mean.

Front

How do you calculate a z-score?

Back

The formula for calculating a z-score is: z = (X - μ) / σ, where X is the value, μ is the mean, and σ is the standard deviation.

Front

What does a positive z-score indicate?

Back

A positive z-score indicates that the value is above the mean.

Front

What does a negative z-score indicate?

Back

A negative z-score indicates that the value is below the mean.

Front

If a z-score is 0, what does that mean?

Back

A z-score of 0 means the value is exactly equal to the mean.

Front

Calculate the z-score for a score of 90 if the mean is 75 and the standard deviation is 4.5.

Back

3.33

Front

What is the area under the normal distribution curve between z=-1.26 and z=0.57?

Back

0.6119

Front

What is the probability that Sarah's next party has between 44 and 53 people if the mean guest count is 50 and the standard deviation is 5?

Back

0.6106

Front

If Adam's z-score on a test is +2.5, what does this mean?

Back

He scored 2.5 standard deviations above the average.

Front

Find the z-score with 22.5% below it.

Back

-0.75