The iq test scores are normally distributed with a mean of 100 and a standard deviation of 15. what is the probability that a person would score between 85 and 115?

The IQ test scores are Normally distributed with mean 100 and standard deviation 15.

Let X be the IQ test score of person.

We have to find the probability that person would score between 85 and 115 is

P(85 < X < 115) =

= P(-1 < Z < 1)

= P(Z < 1) - P(Z < -1)

= 0.8413 - 0.1587

P(85 < X < 115) = 0.6826

The probability that a person would score between 85 and 115 is 0.6826

because linear equations are a lot simpler than quadratics equations, and linear equations formula is a lot easier to memorize. that's why i think they're harder.