Algebra 1
Guided Practice
Z-Score
Name ______________________
Period ______Date ___________
Answer each of the questions fully
1. An Algebra I test that had an average of 72 and a standard deviation of 3:
a. Compute the z-score for Kristi who had a test score of 78
b. If a person has a score of 2.12, do they have a test score above, below, or equal to the
mean?
2. Here are the z scores of the heights for 6 randomly chosen Park View Students.
{  1,  .25 ,  .1, 0, 1.9, 2.1 }
a. How many students are shorter than the normal?
b. How many students are taller than normal?
c. Are any of the students the “normal” height?
3. Consider the following data set: 19, 25, 12, 35, 27, 29, 11, 28, 17, 22, 16, 21
a. What value is two standard deviations above the mean?
b. What value is one standard deviation below the mean?
Algebra 1
Guided Practice
Name ______________________
Period ______Date ___________
Z-Score
4. The mean salary for a math teacher in Loudoun County is $57,000 per year with a standard
deviation of $2500. The mean salary for a grocery bagger at Safeway is $21,000 with a standard
deviation of $1800. Given that each person is very happy with his/her profession, who would
have the more unusually high salary - a math teacher who makes $63,000 or a grocery bagger
who makes $30,000? Why?
5. In the United States as of June 2008, teenagers from the age of 13-17 send/receive 1740 text
messages per month with a standard deviation of 550 text messages.
a. What is the z-score for a teenager who sends/receives 2150 text messages per month?
b. What about a teen who sends/receives 650 texts messages per month?
c.
If a teenager has a z-score of 1.38, about how many text messages did they
send/receive that month?
14.88
Yes
-2
Above
2499
35.73
-1.98
571
Grocery bagger
because the
person had a
higher z-score
2
3
0.75