Question

Assume that adults have IQ scores that are normally distributed with a mean of

mu equals 100μ=100

and a standard deviation

sigma equals 20σ=20.

Find the probability that a randomly selected adult has an IQ between

8484

and

116116.

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The probability that a randomly selected adult has an IQ between

8484

and

116116

is

nothing.

​(Type an integer or decimal rounded to four decimal places as​ needed.)

Answer 1

solution

P(84< x < 116) = P[(84-100) /20 < (x - ) / < (116-100) / 20)]

= P( -0.8< Z < 0.8)

= P(Z <0.8 ) - P(Z <-0.8)

Using z table   

= 0.7881-0.2119

probability= 0.5762