z-score — Algebra II, what it means and where it is taught
How many standard deviations a value sits from the mean: z = x - μσ.
Taught in Algebra II.
Where it is taught
What it rests on
Work through these first if this one does not settle.
- Standard deviation — A measure of typical distance from the mean.
- Mean — Two kinds of centre: the balance point, and the middle value.
Practise this idea
3 questions in the course bank use z-score, in The Normal Distribution.
Problem 1
A value is 2 deviations above the mean. What is its z-score?
Worked answer
2
z=2
Problem 2
Mean 50, deviation 10. Find the z-score of 70.
Worked answer
2
70-5010=2
Problem 3
Mean 100, deviation 15. Find the z-score of 85.
Worked answer
-1
85-10015=-1