Question

In: Statistics and Probability

12. A standard IQ test has a normal distribution with a mean of 100 with a...

12. A standard IQ test has a normal distribution with a mean of 100 with a standard deviation of 15.

a) A score of 145 or higher on this exam is categorized in the gifted realm. What percent of people would be considered gifted? ___________

b) The people who score in the lowest 5% of the standard IQ test are considered to have “mental retardation”. What cutoff score is used to qualify for this benchmark? ___________

Expert Solution

µ = 100

sd = 15

a)

= P(Z > 3)

= 1 - P(Z < 3)

= 1 - 0.9987

= 0.0013

= 0.13%

b)

or, x = 100 - 1.645 * 15

or, x = 75.325 or 75 (approx.)

orchestra answered 2 years ago

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