SOLUTION: Assume that adults have IQ scores that are normally distributed with a mean of 96.5 and a standard deviation 15.4. Find the first quartile Upper Q 1​, which is the IQ score s

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Question 1125871: Assume that adults have IQ scores that are normally distributed with a mean of 96.5 and a standard deviation 15.4. Find the first quartile Upper Q 1​, which is the IQ score separating the bottom​ 25% from the top​ 75%.
Found 2 solutions by Boreal, Alan3354:
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
want the z value corresponding to 0.2500 and 0.7500
That is +/-0.675
z=(x-mean)/sd
so 0.675*15.4=(x-96.5)
10.395=x-96.5, x=106.9, for the 75th percentile and positive z
-10.395=x-96.5, x=86.1, for the 25th percentile and negative z

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
50% of the people are below average.
Seems more like 90%.