00:01
We'll be using our ti -84 to help us find these values.
00:04
And number one, we have the standard normal curve, and we want to know what is the probability of getting a z value that is less than 0 .78.
00:13
And so we'll use that normal cdf, and we'll have in a number.
00:19
If you go to default quite often, it will default to this.
00:22
You can also put in like negative a million.
00:25
And then we'll go to 0 .78, and we'll leave the mean at 0 .0 .0.
00:30
And the standard deviation at one.
00:33
And when we hit that button, we end up getting the value of two, i think you want two thousand places.
00:41
I'll list it as four, and then i'll also list it as two.
00:47
And so ironically, it comes out to be very close to the same answer, but they mean something very different.
00:53
Number two, we have, we want to find what the area to the right of 0 .06 is.
01:00
So again, we'll do the same thing with the normal cdf, except this time with the normal cdf we'll put in .06 and then put in a large number.
01:13
You put in a million, 100 ,000, even 100 will be fine for this.
01:18
So again, normal cdf under second and distribution and that 0 .06 large number and paste it down.
01:29
And you get a value of 0 .4761 to 2 decimal places will be the 0 .48.
01:39
Number three, you have a couple parts here.
01:44
You have a normal distribution with a mean of 9 and a standard deviation of 5.
01:48
And you want to find in part a the likelihood of having a value that is less than 20.
01:53
So again, we're going to use this normal cdf.
01:59
But this time we'll plug in some value like that.
02:04
We'll plug in 20, but now the mean will be 9, and the standard deviation will be 5.
02:12
And negative 1 with lots of zeros, 20, mean of 9, standard deviation of 5, and that value is, and you need four decimal places for this one.
02:25
That is 0 .9861.
02:29
For part b, you want to find the probability that a number will be greater than 6.
02:36
And so the only thing work, wow, we're going to change a couple values here...