Assume that adults have iq scores that are normally distributed with a mean of
105 and a standard deviation 15.
a. find the probabilty that a randomly selected adult has an iq less than 126

P( A randomly selected adult has an IQ less than 126) = 0.91924

Step-by-step explanation:

Let, X be the random variable, IQ of an adult.

According to the question,

X Normal (105,15)

Let, Z =

So, Z Normal(0,1)

Now,

X < 126

⇒ <

⇒Z < 1.4

Now, from standard normal probability table we get

P(Z < 1.4) = 0.91924

So, P( A randomly selected adult has an IQ less than 126) = 0.91924