Question

adults have IQ scores with a mean of 100 and std deviation of 15 the IQ score that is in the third quartile

Answer 1

We have given:

= 100 , = 15

And we have asked to find the IQ score (x) for third quartile.

We know that the area less than third quartile is 0.75.

So by using raw score formula we get-

IQ score (x) = Z_0.75 * +

In excel use the command =NORMSINV(0.75) to get the value of Z_0.75

So we get  Z_0.75 = 0.6745

Hence we get IQ score (x) = (0.6745 * 15) + 100 = 110.1173

Adults have IQ scores with a mean of 100 and std deviation of 15 the IQ score that is in the third quartile is 110.1173 (rounded to 4 decimal places)

Hope this will help you. Thank you :)