Question

Assume that adults have IQ scores that are normally distributed with a mean of 101.3 and a standard deviation 19.9. Find the first quartile Upper Q 1​, which is the IQ score separating the bottom​ 25% from the top​ 75%. (Hint: Draw a​ graph.)

Answer 1

Answer:

87.9

Step-by-step explanation:

Use a calculator or table to find the z-score that corresponds to 25%.

P(Z < z) = 0.25

z = -0.675

Now find the value that corresponds to that z score.

z = (x − μ) / σ

-0.675 = (x − 101.3) / 19.9

x = 87.9