People with z-scores of 2.25 or above on a certain aptitude test are sometimes classified as geniuses. if aptitude test scores have a mean of 100 and a standard deviation of 12 points, what is the minimum aptitude test score needed to be considered a genius
let the minimum score be x z-score is given by: z=(x-μ)/σ where: mean,μ=100 standard deviation, σ=12 z=2.25 thus 2.25=(x-100)/12 solving for x we get: 27=x-100 x=100+27 x=127 Thus the minimum test score is 127 points
