Question

Assume that adults have IQ scores that are normally distributed with a mean of mu equals 105 and a standard deviation sigma equals 20. Find the probability that a randomly selected adult has an IQ between 88 and 122.

The probability that a randomly selected adult has an IQ between 88 and 122 is

Answer 1

Solution :

Given that ,

mean = = 105

standard deviation = = 20

P(88 < x < 122) = P[(88 - 105)/ 20) < (x - ) /  < (122 - 105) / 20) ]

= P(-0.85 < z < 0.85)

= P(z < 0.85) - P(z < -0.85)

= 0.8023 - 0.1977

= 0.6046

The probability that a randomly selected adult has an IQ between 88 and 122 is 0.6046