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 does the mean represent in a normal distribution?

Back

The mean is the average of all data points in a distribution and is the center point of a normal distribution.

Front

What is standard deviation?

Back

Standard deviation is a measure of the amount of variation or dispersion in a set of values. A low standard deviation means that the values tend to be close to the mean.

Front

How do you calculate the z-score?

Back

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

Front

What is the empirical rule in statistics?

Back

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

Front

What is the probability of a value falling within one standard deviation of the mean in a normal distribution?

Back

Approximately 68%.

Front

What is the probability of a value falling within two standard deviations of the mean in a normal distribution?

Back

Approximately 95%.

Front

What is the probability of a value falling within three standard deviations of the mean in a normal distribution?

Back

Approximately 99.7%.

Front

What is a percentile in statistics?

Back

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

Front

What does it mean if a z-score is positive?

Back

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