SOLUTION: Scores on an adult Intelligence Scale (a standard IQ test) are approximately normally distributed with mean of 110 and standard deviation of 5. IQ- N(110, 25) What percent of scor

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Question 1196647: Scores on an adult Intelligence Scale (a standard IQ test) are approximately normally distributed with mean of 110 and standard deviation of 5. IQ- N(110, 25)
What percent of scores are above 110?
I tried:
Z=xi-xbar/s
Z=25-110/5
Z=17
(1-1/z^2)
(1-1/17^2)*100
99.7%
The empirical rule says that it's in between 1-2 standard deviations above the mean.


Answer by ikleyn(52858) About Me  (Show Source):
You can put this solution on YOUR website!
.

Hello,  the normal distribution curve is symmetrical relative to the mean score.

THEREFORE,  the percent of scores above  110  is  50%  in this problem.


It is clear  (and should be clear)  without any calculations.


By the way,  for your better understanding,  when they ask you about the percent above some score,

it means that you should find the  AREA  UNDER  normal curve to the right of the given score.


There is nice online calculator for solving such problems under this link

https://onlinestatbook.com/2/calculators/normal_dist.html


It is for common use and is free of charge.

It provides an accompanying plot,  shoving which area under the normal curve is of your interest.
It prevents you of making errors.

This calculator is  highlight%28highlight%28indispensable%29%29  teaching tool for you,  when you make your first steps in such calculations.


So,  play with it as much until you learn the subject sufficiently.