Use mean and standard deviation to fit normal distributions and estimate population percentages with technology.
Find the z-score of a value given the mean and standard deviation
Problem
What is the \(z\)-score for this value: \(x=86\), mean \(80\), sd \(3\)?
Big Picture
What this problem is really about
A z-score converts raw distance from the mean into standard-deviation units. Subtract the mean from the value in that order, then divide by the positive standard deviation. The sign tells whether the value lies above or below the mean, while the magnitude tells how many standard deviations away it lies.
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