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Percentile rank & Inter-quartile range

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For a normally distributed test with a mean of 100 and standard deviation of 20:

a) What score would be associated with the 80th percentile?
b) What would the inter-quartile range be for the test?
c) What would be the percentile rank of a score of 125?

Please give detailed notes explaining the steps required to answer each of these questions.

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Solution Summary

This solution provides detailed explanations of how to find percentile ranks and inter-quartile range for normally distributed data.

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The following functions are to be used in an Excel file. The Excel file is attached below.

For a test with a mean of 100 and standard deviation of 20:

a) What score would be associated with the 80th percentile?

Step 1:
We need to find the standard score below which 80% of the scores lie in a normal distribution. For this, we will use the NORM.S.INV(probability) function. We enter .80 for the probability.

Standard score = 0.841621234

Step 2:
We need to find the original score that 0.8416 corresponds to. The formula for obtaining a ...

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