Calculate z-score of 80, mean 80, sd 6

Step by step

The question

Question: find the z-score of 80, when the mean is 80 and the SD is 6.

A z-score tells how many SDs a number is from the mean.

1 Write the formula

z is x minus the mean, all over the SD.

Careful!

Subtract first, then divide.

The whole top is divided by the SD.

2 Put the numbers in

The top first: 80 minus 80 is 0.

Then 0 divided by 6 is 0.

3 Read it

80 on a number line with the SD marks.

The z numbers count the SDs.

So 80 is right on the mean.

4 Check

Let's check: start at the mean and go 0 SDs.

80 plus 0 times 6 is 80.

So it is right!

Let's look back.

First: write the formula.

Then: put the numbers in.

Then: read it.

Last: check.