>> I'm going to show you the answer to this, by doing it in a spreadsheet. You
could do all of these calculations, without any technology. And if you did that,
that's really great. It's always really good practice to calculate things
without using any technology, but just for the purposes of figuring out the
standard deviation, technology can really speed along this process. So I'm not
going to use any shortcuts here. We're going to do it exactly as we would if we
didn't have technology. So first we need to take the avearage of all of these,
we're going to sum them up. So we're taking the sume of all of these. I could
also just write equals a1 plus a2 plus a3 all the way to a10. And we'd get the
same thing. But why would we do that if we can simply write this. Now to take
the average all we do is divide by the number of values which is 10. So that's
just going to be 51,511.1. Alternatively, the nice thing about technology is we
can just do this. Take the sum, and divide by the total number. Do it all in 1
step. So now we have the average. Now we're going to subtract the average from
each 1 of these values. Not the opposite, where we subtract each of these values
from the mean. That's an important distinction. In this case, it doesn't matter
as much but in other statistical concepts that's an important distinction to
make. So we'll write equals A1 minus. The mean. So I'm subtracting the mean from
each of these values. Now I could just do the same thing here and write equals
a2 minus the mean but that would be tedious. We can just drag this down. When
you do that, remember that there has to be a little plus sign there. That means
you're successfully dragging it down. If you went like this, it won't do
anything. It'll just highlight the boxes. So here, we have the deviations from
the mean. Here, in the next column We're going to square each deviation. Equals
b1 squared. And again, we're going to drag it down. So we have the squared
deviations for each of these values. Now remember that the variance is the
average squared deviation. So we could just write. Average of c1 to c10. But I
want to make sure we go through all the other steps in between. So let's again
practice calculating the average just for clarity's sake. So the variants then
would be the sum of c1 to c10. Remember that's how you start out taking the
average, and then divide by 10. So here's the variance, and then the standard
deviation is simply the square root of the variance. So we'll write equals SQRT.
That's the shortcut for square root. And then we can just see C13. So we know
that the standard deviation is 6557.16 approximately. Now I want to point out
something really important before we finish this solution video. Here I simply
said equals square root of this cell C13. Whereas here, I wrote out the
whole average. The reason for that is because say I had but this all here, A13.
Then, when we drag it down, we don't get the right deviations. And we can double
click on it, and see what it did. Here, it took A4 minus A16, whereas here it
took A1 minus A13, which is what we wanted. But we want it to always stay A13,
which is why we have to make sure this is a constant. And the way to make sure
it's a constant is by just writing it. Notice also that all of these values
changed when these values changed because all these values are dependent of
these values So when we change it back we should again get the correct standard
deviation.