Question

(4pts) Assume that adults have IQ scores that are normally distributed with a mean of 100 and a standard deviation of 15 (as on the Wechsler test). Find the IQ score separating the top 14% from the others

A) 83.7
B) 116.2 C) 108.6 D) 99.3

Answer 1

Answer: 116.2 (choice B)

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Step-by-step explanation:

We need to find a value of k such that P(X > k) = 0.14

This is equivalent to P(X < k) = 0.86 since 1 - 0.14 = 0.86

Use the invNorm function on a TI84 calculator or similar to input invNorm(0.86,100,15). The result is approximately 116.205 which rounds to 116.2

If you do not have a TI84 or similar, then you can input invNorm(0.86,100,15) into WolframAlpha. It is a free online calculator that can do many tasks beyond a basic calculator. There are many other online calculators that are similar.