Please help me I don’t have time

Question

Find the standard deviation for the set of data

{12,20,7,18,25,6,17,26,16}

A. 6.65

B. 8.22

C. 6.09

D. 6.3

Answer 1

To do this calculation manually, you need to build a table like this:

In the first column, put the numbers. Take the average by adding them all up and dividing by the number of numbers. The sum is 147. The number of numbers is 9. So the average is 147/9 = 49/3.

The second column is this average subtracted from each number.

The 3rd column is the second column squared.

Now, add up the 3rd column. The sum is 398. Now divide that by the number of numbers (which was 9) to get the Variance. The Variance is 398/9. Now take the square root of that and the answer is the standard deviation. So the standard deviation is √(398/9) = 6.64998

OR, if you have a TI-84 calculator, you can put the numbers into a list and push a button or two to get the calculator to do this all for you. Let me know if you want me to explain this process.