Question

Scores of an IQ test have a​ bell-shaped distribution with a mean of 100 and a standard deviation of 20. Use the empirical rule to determine the followinWhat percentage of people has an IQ score greater than 120?

Answer 1

Percentage of people with IQ greater than 120 is 84.134%

Explanation:

First thing we do here is to calculate the

z-score

Mathematically;

z-score = (x-mean)/SD

here, x = 120, mean = 100 while SD = standard deviation = 20

z-score = (120-100)/20 = 20/20 = 1

The probability we want to calculate is;

P(x > 120) or P(z >1)

we proceed to use the standard score table to get this;

From the standard score table ;

P(z >1) = 0.84134

which is in percentage = 84.134%