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Calculating
Percentages from
Z-Scores
Finding Normal Percentiles
• You can find a percentile using the
Normal Density Curve
• First calculate the z-score
• You find the percentile using a z-
score either from a table or a
calculator.
• Using the table – see video
• Using the calculator – see video
Finding the percent of data
between 2 z-scores
• Calculate each z-score
• Calculate the percentile value for
each z-score
• Subtract the percentile values to find
the percent of data between the 2 z-
scores

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Calculating percentages from z scores

  • 2. Finding Normal Percentiles • You can find a percentile using the Normal Density Curve • First calculate the z-score • You find the percentile using a z- score either from a table or a calculator. • Using the table – see video • Using the calculator – see video
  • 3. Finding the percent of data between 2 z-scores • Calculate each z-score • Calculate the percentile value for each z-score • Subtract the percentile values to find the percent of data between the 2 z- scores