00:01
Hello there and welcome.
00:02
Before we launch into this question, let's review a little bit about our bell curves.
00:08
So our bell curve looks something like this, where this right over here is going to be the mean, and this is kind of like the partitions.
00:21
So they say that in a perfect distribution, about 68 % of the data approximately is within one standard deviation of the mean.
00:30
So if you look back to the question, it's asking us for a sample size of 30 from this population, about 68 % of 0 .3 % of the means will be in what interval.
00:43
So we can say that 68 .3 % of the sample is going to be within one standard deviation of the mean.
00:53
So really, it just creates a sort of range.
00:56
And the range that it looks like is going to be the mean minus, the standard deviation over the square root of n and the mean plus the standard deviation over the square root of n right because it's a range we're looking at here because there's two boundaries there's this boundary and there's this boundary so we're doing the same thing here we're doing minus this much and plus this much and now we're just going to substitute the values that we do know so the mean we know is 250 minus standard deviation oh, we were given that too.
01:39
We know that that's 65 and it's square root of n...