Question

The IQ scores of a population are normally distributed with a mean of 100 and a standard deviation of 15. What percentage of the population would be recognized as having an IQ score between 115 and 130? Round to the nearest tenth.(1 point)

9.9%

35.5%

84.1%

13.6%
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Answer 1

Compute z-scores: z1 = (115−100)/15 = 1.0, z2 = (130−100)/15 = 2.0.
Area between z = 1 and z = 2 = Φ(2) − Φ(1) ≈ 0.97725 − 0.84134 = 0.13591 ≈ 13.6%.

Answer: 13.6%