Math 3
1-5 Standardized Values and Percentiles Extra Practice
z
Name__________________________________
x

1.
A standard normal distribution (a distribution of z-scores) has a mean of 0 and a standard deviation
of 1. Sketch a standard normal distribution below.
2.
On a standard normal distribution, what is P  z  1 ? ___________
Data for newborn babies is given in the table below. Use this data to answer the rest of the problems
on this worksheet.
Newborn Baby Weights

7.5

1.25
3.
If a baby Jane has a weight of 8.5 pounds, what is the z-score for baby Jane?
4.
What is the percentile for baby Jane? As a first step, make a sketch of a standard normal distribution to
help you solve the problem. Write your answer using correct probability notation.
5.
Baby John weights 9.5 pounds at birth. What is baby John’s z-score?
6.
What percent of babies are born heavier than baby John? As a first step, make a sketch of a standard
normal distribution to help you solve the problem. Write your answer using correct probability
notation.
Newborn Baby Weights

7.5

1.25
7.
What is the probability that a newborn baby has a weight between baby Jane and baby John? As a first
step, make a sketch of a standard normal distribution to help you solve the problem. Write your answer
using correct probability notation.
While we used z-scores to help us solve problems 3-7, thanks to our calculator we are able to solve
problems such as those without calculating a z-score.
8.
Baby Gregory weighs 6.5 pounds at birth. What is baby George’s percentile? As a first step, make a
sketch of a normal distribution (with the above statistics) to help you solve the problem. Write your
answer using correct probability notation.
9.
Baby Georgina weighs 5.25 pounds at birth. What percent of babies weigh more than 5.25 pounds at
birth? As a first step, make a sketch of a normal distribution (with the above statistics) to help you solve
the problem. Write your answer using correct probability notation.
10.
What is the probability that a newborn baby has a weight between Baby Gregory and Baby Georgina?
As a first step, make a sketch of a normal distribution (with the above statistics) to help you solve the
problem. Write your answer using correct probability notation.