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CAN SOMEONE HELP ME PLEASE?
A well-known standard I.Q. test produces normally distributed results with a mean of 100 and a standard deviation of 15. What percent of the population have an I.Q. between 91 and 109?
a. 27.34%
b. 45.32%
2 Answers
- ?Lv 72 years ago
With what in particular? Cool!
91-109 is 100±9, which is ±3/5 of a Standard Deviation of 15.
The Empirical Rule or 68-95-99.7% Rule says that within 1 SD of the mean is about 68% of the population.
3/5 of 68 is a little more than 40%, so I would go with answer b. 45.32%
Rules of thumb are useful for eliminating the less likely of the two choices.
