00:02
Because we're finding the probability for an average weight, we need to apply the central limit theorem, which says if we repeatedly took samples of 30 dogs and calculated the average weights, the weights would be normally distributed, the average weights would be normally distributed, with a center at the population average, which in this case is five.
00:24
And then the standard deviation or standard error of all those samples is found by taking our population standard deviation.
00:32
3 .5 and dividing it by the square root of our sample size 30.
00:37
So when we do that 3 .5 divided by the square root of 30 makes 0 .639.
00:46
So that means on my bell curve here i'm going to number to the right and to the left by 0 .639.
00:52
And i've marked where 4 and 7 are because we want the probability that the average weight is between greater than 4 and less than seven.
01:05
So between four and seven.
01:07
So we're interested in this area in here.
01:10
So to figure that out, we're going to need to calculate a z score for four by doing four minus the mean divided by our standard deviation...