00:01
We're told that the inside diameter of a randomly selected piston ring is a random variable with a mean value of 12 centimeters and the standard deviation of 0 .04 centimeters.
00:13
In part a, we are given x bar, which is the sample mean diameter for a random sample of 16 rings.
00:23
And we're asked to find the sampling distribution center for x bar and the standard standard deviation.
00:33
Of the x bar distribution.
00:40
So we have the sampling distribution of x bar.
00:59
This is going to be centered at the expected value of x bar, which we know by the result from the section is the mean mu, which we were given was 12 centimeters.
01:23
And we have that the standard deviation of the x bar distribution.
01:45
Well, this is going to be the standard deviation of x bar, which again we know from a result in this section, this is the standard deviation of the random variable x, which represents the inside diameter of a randomly selected piston ring over square root of n.
02:18
We have that the standard deviation we were given was 0 .04, and the number of samples n is 16.
02:32
So over root 16, which is equal to .01 centimeters.
02:48
Next, in part b, we're asked to answer the questions from part a for a sample size now of 64 rings...