00:01
This problem says the monthly demand for a product is normally distributed with a mean of 700 and a standard deviation of 200.
00:07
Question 1 says what is the probability demand will exceed 900 units in a month? and question 2 says what is the probability that the demand will be less than 392 units in a month? and to answer both of these questions we're going to use normal cdf and our graphing calculator or computer software because with our mean and standard deviation, if you want to know the probability that your observation will be below a certain value or above a certain value or between two values, you can use this operation, the normal cdf, as long as you have four numbers.
00:38
And the numbers you need are the lower bound, the upper bound, the mean, and the standard deviation.
00:47
So in our first example for our probability that it will exceed 900, if we want to exceed 900, that means we want to be greater than 900, which means we want the probability that our observation will fall to the right of 900 in this normal distribution curve.
01:01
So our lower bound will be 900, and we want to encompass everything to the right underneath the normal curve.
01:06
So we'll use positive infinity just to make sure we cover everything, and then our mean of the given 700 and also the given standard deviation of 200...