If I already found my standard deviation for a problem and the mean, then how do I find the amount within one standard deviation of the mean?

Question

kropot72 · Answer

The empirical rule states the following:
Approximately 68% of the data points lie within the range plus and minus one standard deviation of the mean.

anonymous · Answer

okay so if my numbers are 80, 105, 120, 175, 185, 190, 205, 210, 215, 300, 320, and 325 my mean is 202.50 and my standard deviation is 76.96. would that mean that 6 are within the range?

phi · Answer

you would look for all numbers within the range  202.5 - 79.96 to 202.5+79.96

anonymous · Answer

oh okay thank you. That is what I did. I wasn't sure I did it right! :)

anonymous · Answer

Okay so within with two standard deviations do I just do the same twice?

phi · Answer

However, are you sure about your std ?

anonymous · Answer

not now

phi · Answer

never mind,  I think you are correct.  It depends if you divide by N  or N-1

anonymous · Answer

oh okay phew

anonymous · Answer

Thank you for the help. I was panicking..