Percentiles and Z-scores

Front

The median represents the ______ percentile

Back

50th

Front

Who ranks higher in his own league, George or Bill? George has an average bowling score of 180 (mean: 150, SD: 20) and Bill has an average score of 190 (mean: 160, SD: 15).

Back

Bill, because his standardized score is higher than George’s.

Front

A z-score measures

Back

The distance from the mean of a given data point, measured in standard deviations.

Front

What are the mean and standard deviation of z-scores?

Back

Mean: 0, Standard Deviation: 1

Front

What percent of large lids are too small to fit if the diameter follows a Normal distribution with mean 3.98 inches and standard deviation 0.02 inches?

Back

6.68%.

Front

Define percentile.

Back

A percentile is a measure used in statistics indicating the value below which a given percentage of observations fall.

Front

What is a z-score?

Back

A z-score indicates how many standard deviations an element is from the mean.

Front

How do you calculate a z-score?

Back

Z = (X - μ) / σ, where X is the value, μ is the mean, and σ is the standard deviation.

Front

What does a z-score of 0 indicate?

Back

A z-score of 0 indicates that the data point is exactly at the mean.

Front

What is the significance of a negative z-score?

Back

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