00:01
For this problem, we are told that a machine produces metal pieces that are cylindrical in shape.
00:05
A sample of pieces is taken, and the diameters are found to be 1 .01, 0 .97, 1 .03, 1 .04, 0 .99, 0 .98, 0 .99, 1 .01, and 1 .03 centimeters.
00:23
We are then asked to find a 99 % confidence interval for the mean diameter of pieces from this machine, assuming an approximately normal distribution.
00:32
So the first step here is to recognize that we have n equals, let me just double check here.
00:41
I believe that this is going to be, yes, n equals nine.
00:46
So we then want to find the mean, x bar, or the sample mean.
00:51
That would be equal to the sum of each one of our data points.
00:54
So 1 .01 plus 0 .97 plus dot dot dot, dot, plus 1 .03, all divided by 9.
01:03
And we'll end up finding that the sample mean here is going to be approximately 1.
01:10
But to be a little bit more precise, it would be 1 .00, or excuse me, 1 .005.
01:18
Then, or actually, 1 .006 would be a more accurate rounding.
01:24
Then we want the standard deviation...