Let the random variable X represent the demand and assume that X has a Normal distribution with = 20,000.Now we need to figure out the standard deviation for the distribution. The senior forecaster predicted that there is a 0.9 probability that the demand will be between 10000 and 30000 units. This means that theMIDDLE 90%of the demand distribution is between 10000 and 30000. What is the probability that the demand is less than 10000?

Answer= 0.05

Using your answer to the previous question, find the z-score corresponding to the probability that the demand is less than 10,000 units (Hint: Use the Norm.S.INV function in Excel). Type theabsolute value of the z-score to three decimal placesin the space below.

Answer= 1.645

Now, take theabsolute valueof the difference between the mean that you found earlier and either 10000 or 30000 (doesn't matter which, answer will be the same). Divide that difference by the z-score you found in the previous question, and round the result to the nearestones place(no decimal). This is the standard deviation of the demand distribution. Place your answer for the standard deviation of the demand distribution in the space below. Remember - the answer is a whole number.

(Edited) The first two questions apply to the third. The third question is the one I am having trouble with. If there is any other information that you believe I am missing in order to complete the third question please be more specific as to what I can provide.