# Normal Distribution problem; demand and inventory

This question is asked on an upcoming homework assignment:

The weekly demand for a product approximately has a normal distribution with mean 1,000 and standard deviation 200. The current on hand inventory is 2,200 and no deliveries will be occurring in the next two weeks. Assuming that the demands in different weeks are independent:

$a)$ What is the probability that the demand in each of the next two weeks is less than 1,100?

$b)$ What is the probabbility that the total of the demands in the next two weeks exceeds 2,200?

I don't even know where to begin.

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a) How many standard deviations is $1100$ from $1000$? You need to consult either a table or an electronic friend to find the probability that a normal distribution deviates from the mean to one side by less than that many standard deviations. Then you need apply the definition of independence to find the probability of the two independent events both occurring from their individual probabilities.
@Imray: $1000$ is the mean of the weekly demand, and $1100$ is the bound of the weekly demand that's given. –  joriki Oct 14 '12 at 6:02