SOLUTION: Assume that adults have IQ scores that are normally distributed with a mean of 100.1 and a standard deviation 20.5. Find the first quartile Upper Q 1​, which is the IQ score sepa

Algebra.Com
Question 1135421: Assume that adults have IQ scores that are normally distributed with a mean of 100.1 and a standard deviation 20.5. 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 by Boreal(15235)   (Show Source): You can put this solution on YOUR website!
z=(x-mean)/sd
z for 0.2500 probability is -0.675
-0.675=(x-100.1)/20.5
x=86.26 Q1
Q3 is the same distance on the other side
x=113.94 Q3. That is the upper quartile. The phrasing of the question is a little ambiguous here.

RELATED QUESTIONS

Assume that adults have IQ scores that are normally distributed with a mean of 100 100 (answered by richwmiller)
Assume that adults have IQ scores that are normally distributed with a mean of 105 and a... (answered by ewatrrr)
assume that adults have IQ scores that are normally distributed with a mean of 105 and a... (answered by ewatrrr)
Assume that adults have IQ scores that are normally distributed with a mean of 105... (answered by Boreal)
IQ scores of adults are normally distributed with a mean of 100 and a standard deviation... (answered by stanbon,ewatrrr)
Assume that adults have IQ scores that are normally distributed with a mean of 102.6 and... (answered by VFBundy,dkppathak)
Assume that adults have IQ scores that are normally distributed with a mean of 105... (answered by Boreal)
Assume that adults have IQ scores that are normally distributed with a mean of 105 and a... (answered by ewatrrr)
Assume that adults have IQ scores that are normally distributed with a mean of 100100 and (answered by Boreal)
Assume that adults have IQ scores that are normally distributed with a mean of 95.5 and a (answered by Boreal)