Z = (score-mean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (.8000) and its Z score. Insert Z score in the equation above and solve for score.
4. The average family income in the town of Seneville is $45 000, with a standard
deviation of $9000. Assuming that family income is normally distributed,
determine the income level below which 80% of the families in this town earn
1 answer
1 answer