Percentiles Practice

Front

What is a percentile?

Back

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

Front

What does a Z-score represent?

Back

A Z-score indicates how many standard deviations an element is from the mean. A Z-score of 0 indicates the score is identical to the mean.

Front

How do you calculate a Z-score?

Back

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

Front

What does a negative Z-score indicate?

Back

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

Front

What does a positive Z-score indicate?

Back

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

Front

If the mean is 30 and the Z-score is -1, what is the standard deviation if the value is 25?

Back

The standard deviation is 5.

Front

What is the 50th percentile also known as?

Back

The 50th percentile is also known as the median.

Front

How do you find the median in a data set?

Back

To find the median, arrange the data in ascending order and locate the middle value.

Front

What is the formula for calculating the percentile rank of a score?

Back

Percentile Rank = (Number of values below X / Total number of values) * 100.

Front

What does a Z-score of -1.5 mean?

Back

It means the score is 1.5 standard deviations below the average.