Question

How do you plug these numbers into the calculator? TI-84 Plus CE

Assume that adults have IQ scores that are normally distributed with a mean of 100 and a standard deviation of 15 (as on the Wechsler test). Find the IQ score separating the bottom 40% from the top 60%.

Answer 1

We have given " normal distribution "

μ = mean = 100

σ = standard deviation = 15

Bottom area = 40 %

we convert the bottom area in to decimal

Bottom area = 0.40

path for Ti -84 and Ti -83 calculator

Press " 2ND "

Press " vars "

Select " invNorm"

While using " invNorm " function we always plug area means bottom area in decimal

Area = 0.40

μ = 100

σ   = 15

i.e invnorm( 0.40 . 100 . 15 )

Press " Enter

From Ti - 84 and Ti -83 we get

96.19979348

IQ score separating the bottom 40% and top 60 % = 96.19979348

This is the required answer

IQ score separating the bottom 40% and top 60 % = 96.19979348