IQ Score of normal distribution

Question

Assume that adults have IQ scores that are normally distributed with a mean of 100 and standard deviation of 20. Find the probabilty that a randomly selected adult has an IQ between 80 and 120. 

 

The probabilty that a randomly selected adult has an IQ between 80 and 120 is ______. (Round to 4 decimal places as needed). 

Answer 1

You can easily do this on a calculator if you have a TI 83/84 calculator. You can press 2^nd>DIST (above VARS) and scroll to normcdf()

Input normcdf(lower,upper,mean,standard deviation)

      =normcdf(80,120,100,20)=0.6827

 

If you would like me to explain how to do it using tables I can!