Answer: 0.6827
Step-by-step explanation:
Given : Mean IQ score :
Standard deviation :
We assume that adults have IQ scores that are normally distributed .
Let x be the random variable that represents the IQ score of adults .
z-score :
For x= 90
For x= 120
By using the standard normal distribution table , we have
The p-value :
Hence, the probability that a randomly selected adult has an IQ between 90 and 120 =0.6827