standard deviation and variance

soo this week we learned about standard deviation and variance. I am going to show you a few important things you need to know in order to do these types of problems. So here are the formulas.

• 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.

So now that i have showed you the information you need to know i will show you how to do a problem.

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 thats how you work it!!