Normal Distribution

Suppose that the call-for for a association’s result in weeks 1, 2, and 3 are each normally arranged and the average call-for during each of these three weeks is 50, 45, and 65, respectively. Imply the model hiatus of the call-for during each of these three weeks is known to be 10, 5, and 15, respectively. It turns out that if we can feign that these three call-fors are probabilistically dogged then the completion call-for for the three week era is to-boot normally arranged. And, the average call-for for the full three week era is the sum of the personal averages. Likewise, the antagonism of the call-for for the full three week era is the sum of the personal weekly antagonisms. But be careful! The model hiatus of the call-for for the full 3 week era is not the sum of the personal model hiatuss. Square roots don’t composition that way! In 250 say counterpart.   Now, imply that the association currently has 180 units in supply, and it conciliate not be receiving any advance shipments from its supplier for at smallest 3 weeks. What is the verisimilitude that the association conciliate run out of units?