# Finding percentiles of known normal distributions

All standard IQ test scores are normally distributed and are set up so that the mean score is 100. However, the standard deviation differs from test to test. For example, the standard deviation on the Otis-Lennon test is 16, while the Cattell's standard deviation is 24. The following are three famous high IQ societies, with the number in parentheses showing what percent of the population qualify for membership (i.e., to be in the Triple Nine Society, you must have an IQ in the top one-tenth of one percent in the general population). For each society, determine what score is necessary on each of the two IQ tests listed above to qualify for membership.

a. Mensa (top 2%)

b. Intertel (top 1%)

c. Triple Nine (top 0.1%)

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#### Solution Preview

This solution shows how to find percentiles of known normal probability distributions. Please see the attached Word document for calculations and detailed explanations.

5. All standard IQ test scores are normally distributed and are set up so that the mean score is 100. However, the standard deviation differs from test to test. For example, the standard deviation on the Otis-Lennon test is 16, while the Cattell's standard deviation is 24. The following are three ...

#### Solution Summary

This solution shows how to find percentiles of known normal probability distributions.