Recall that score son the Wechsler IQ test are normally distributed with mean 100 points and standard deviation 15 points.
a. A student’s IQ is at the 87th percentile. Find the student’s IQ. Is it an unusual IQ? Explain.
b. Alexis Martin, who just turned 3 years old, has an IQ of 160 points. She learned to read when she was just 2 years old (Source: New York Daily News). What is her z-score? Does she have an unusual IQ? Explain.
c. Actress Geena Davis reportedly has an IQ of 140 points (Source: CBS News). Sir Isaac Newton, who shares credit with Gottfried Leibniz for inventing calculus, has been estimated to have had an IQ of 190 points. Find the percentiles for Davis’s and Newton’s IQs. Do your equal results mean that Davis is as intelligent as Newton was? Explain.