00:01
For this question, there's given a normal distribution, and the mean and the standard deviation was given in the question.
00:07
Let me just take this note.
00:09
The main value, which is denoted by mu, that is equal to 4200.
00:14
And the next one is the standard deviation.
00:18
So the standard deviation, that is denoted by sigma, which is equal to 900.
00:26
So since this is a normal distribution, i can define the random variable x, which is normally distributed, that is 4 ,200.
00:33
And 900 great so in part 8 what we have to do we have to find we have to find that the problem that more than 5 ,000 acres will be burn in any year so the probability of x is greater than 5 ,000 so what that means if i just graph the normal distribution here the mean score is here which is 4200 and here is 5 ,000 so we have to get the area of this region in order to get this area, i'm going to use the normal cdf function for the graphing calculator.
01:11
When we look at this shaded region, the lower boundary is 5 ,000, and there is no in upper boundary.
01:17
That goes to infinity, so i'm going to put very big number here.
01:21
And the mean value is 4 ,200 in the standard division, 900.
01:25
Let me just put these values on the calculator.
01:28
Just press second in distribution.
01:30
You will see on the screen there's a normal cdf.
01:33
The lower boundary here is 5 ,000 and the upper boundary, which is one, this is in 99.
01:40
And the mean value is 4 ,200 and the 900.
01:46
Great.
01:46
Let's get the result.
01:48
So the probability here, how many decimal points do we need? let me just check this one here.
01:55
So nothing is sad here.
01:57
Yeah, four decimal places.
01:58
So the answer would be 0 .18 and 17.
02:03
This is the probability for the first case.
02:06
What about for part b? the terminated problem that fewer than 4 ,000, right? and so that means we need to get the probability of x is less than this is 4 ,000.
02:22
So again, i'm going to use the normal cdf function here.
02:27
The normal cdf...