Standard Deviation and Variance

Okay, so this week I am going to teach you how to work problems using standard deviation and variance. This might seem hard at first but it really easy after you know what everything stands for you. So first your going to need to know a few things.

• The formula used for these problems is s^2 = ((∑(xi^2)) / (n)) - x̅ ^2
• When you see the symbol, ∑ it means the sum.
• The symbol xi stands for the numbers.
• x̅ stands for the mean of the numbers.
• The letter n stands for the amout of numbers being used in the problem.
• When working these problems, you might find it easier by setting up a chart with two columns.
• Also, when working these problems, you might find it easier by finding everything first then plugging it into the formula given above.

Okay, so now that you know the basics of working these problems, I am going to work an example for you.

Example 1: Find the standard deviation of 5, 5, 7, 8, and 10.

• The first thing you are going to do is find everything.
• n is going to be 5.
• x̅ is going to be 7.
• ∑(xi^2) is going to be 263
• Once you find everything you can, you plug it into the formula.
• Your answer is going to end up being 1.897

And that's it for this week. BYEE.

--Halie