00:01
So in this particular problem, you're told that the mean is 1 .1, and the standard deviation is 0 .1 pounds.
00:07
And we want to know the proportion of stakes that weigh less than 0 .9 pounds.
00:12
A couple of ways you can do this.
00:13
One way is to calculate the z score to standardizer information.
00:17
So 0 .9 minus 1 .1 divided by 0 .1.
00:23
And this is exactly negative 2.
00:26
You could have also done this by hand by simply subtracting the standard deviation.
00:29
But i've got it, so now what i need to do is i need to calculate the percent or the proportion that's below negative 2.
00:39
So if i go to my table, here's negative 2 .0, and i see that their intersection is 0 .028.
00:52
I could also use my calculator on this one.
00:56
So second vars, i'm going to do normal cdf.
01:04
I have to do a weird thing with the calculator.
01:06
To let the calculator know i want less than, but there is no lower bound.
01:11
My upper bound is 0 .9.
01:14
I can use the mean and the standard deviation is given.
01:24
And then you can see that this is 0 .028, which is what we got from the table.
01:36
Now we're told we have a sample size of 8...