00:01
Okay, so first here, first part, so stock running out, we check the independent demands.
00:07
We have week one, the mean is 50, standard deviation is 10.
00:11
Week two, mean 45, standard deviation 5.
00:14
And week three, mean 55, standard deviation 15.
00:17
So if we, the total demand over these weeks, the total mean is 50 plus 45 plus 55, which is, and then the total variance is going to be 10 squared plus 5 squared plus 15 squared is 100 plus 25 plus 225, that's going to be 350.
00:42
And then the standard deviation is the square root of that.
00:45
So the square root of 350 is approximately 18 .71.
00:52
So to find then the probability of the stock will run out.
00:55
In other words, the demand exceeds 180 units, we find the z score for 180.
01:02
For our z score, we take 180 minus 150 divided by the standard deviation of 18 .71, giving us a z score of about 1 .603.
01:14
So using then the z table for the z score of 1 .603, the corresponding probability is about 0 .9452...