Find the population standard deviation and round to one more place than the data

Question

15,18,13,9,12

Answer 1

Greetings!

I have solved for this question in this video. I hope this helps. Check it out and let me know if you have any additional questions.

Take care,

Dr. Christal-Joy Turner

Answer 2

Hi Diane,

I know a couple ways to do this. First and simplest is to use a TI-80s series calculator. Input into a list STAT-EDIT-enter all values. Then go to STAT-CALC-1-Var Stats List number. This will return a value Sigma_x. Make sure you record this and not the sample standard deviation s_x.

Second way is by hand. First, you need the mean, so compute:

(15 + 18 + 13 + 9 + 12)/ 5 = 13.4

Sigma_x = sqrt( Sum(x_i - xbar)²/5

So, you would start with:

Sigma = sqrt (15 -13.4)² + (18 - 13.4)² and so on. Then divide by 5. This will give you your population standard deviation.

Remember, you are rounding to one more place than your data, so that means one decimal in this case. I hope this helps.