Thank you for the opportunity to help you with your question!

Square each of the differences from the previous step and make a list of the squares.

You need to square each of the numbers

Your list of squares is 441,441,225,324,225

Add the squares from the previous step together =1656

Subtract one from the number of data values you started with.

One less than this is 5-1 = 4.

Divide the sum from step four by the number from the previous step.

The sum was 1656, and the number from the previous step was 4. You divide these two numbers 1656/4 =41 4.

Take the square root of the number from the previous step. This is the standard deviation. standard deviation is the square root of 414, which is 20.34698 to the nearest tenth is 20.3.

Please let me know if you need any clarification. I'm always happy to answer your questions.

yes it means that you missed a step,because the value you gave as differences already implies that you have subtracted the values from the mean which is the first step in calculating the sd....then the other steps follow systematically