You have to find the z-score.
z =(85-100)/15
z=(115 - 100)/15
Then you have to use a z-table or a calculator to find the area between the two z scores
You have to look at the table and find the z-score for the 90th percentile.
once you have the zscore
z = (x-100)/15
The IQ scores are normally distributed with a mean of 100 and a SD of 15.
A) What is the probability that a randomly person has an IQ b/t 85-115? Show work
B) Find the 90th percentile of the IQ distribution?
C) If a random sample of 100 people are selected, what is the SD of the sample mean?
1 answer
1 answer