assume that adults have IQ scores that are normally distributed with a mean of 105 and a standard deviation of 15 find the probability that a randomly selected adult has an IQ between 89 and 121 ?

Answer 1

Convert to z-score using
(X-μ)/σ
where X=89 or 121, σ=15, μ=105.
Look up normal distribution table to find probability enclosed between these two z-scores.

Answer 2

43