Percentiles and Normal Distribution Review

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 it mean if a score is in the 70th percentile?

Back

It means that the score is higher than 70% of the scores in the distribution.

Front

What is the mean in a normal distribution?

Back

The mean is the average of all data points and is the center of the normal distribution curve.

Front

What is standard deviation?

Back

Standard deviation is a measure of the amount of variation or dispersion in a set of values.

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

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 proportion of data falls below the mean in a normal distribution?

Back

50% of the data falls below the mean in a normal distribution.

Front

What is the significance of the area under the normal distribution curve?

Back

The area under the normal distribution curve represents the total probability of all outcomes, which equals 1.

Front

If a miniature horse weighs 140 pounds, what proportion weighs less than this weight?

Back

2.5% of miniature horses weigh less than 140 pounds.

Front

What proportion of miniature horses weigh between 185 and 320 pounds?

Back

81.5% of miniature horses weigh between 185 and 320 pounds.