Norman Distribution using the empirical rule.

Question

Scores on an IQ test for people aged 20-34 are normally distributed with a mean of 110 and a standard deviation of 25. What percent of people in the age group have scores above 160?

Answer 1

You use the standard normal distribution table or z - table where

z = ( x - µ ) / σ where µ is the mean and σ is the standard deviation.

We have Pr ( x >160 ) = Pr ( z > ( 160 - 110 ) 25 ) = Pr ( z > 2 )

From the table we see that probability is.0228 or about 2.3%