0:00
All right, you have two questions here.
00:01
The first one is it says a distribution of values is normal with a mean of 43 .2 and a standard deviation of 61 .9.
00:10
You're trying to find what they're calling p94, which is the value that separates the lower 94 % of this distribution.
00:23
The first step in that process is going to be to find a z value for that number, a z score for that number.
00:30
And we're going to have to use the percentage that we're given to find it.
00:34
So i'm going to go to a z table, and i'm going to look up 0 .94 to try to find that z value.
00:48
Okay, so looking for 0 .94, the closest thing we can find, looks to be right here.
00:59
And it looks to me like 0 .94 would be exactly in the middle of those two highlighted values.
01:08
So the z score that i'm looking at would be a 1 .55, right in the middle, 5.
01:15
So i'm going to say 1 .555 is the z score that is associated with 94 % of the data being below it.
01:27
Okay, so now we'll bring that back, and now we know what z is, 1 .555.
01:34
Now we'll have to use a z score formula, which is where we take our x value, which is what we're looking for.
01:41
Minus the mean divided by the standard deviation.
01:46
So we know what z is.
01:47
It's 1 .555.
01:50
X is unknown.
01:52
Mean is 43 .2.
01:55
And standard deviation is 61 .9.
01:58
And now it just doesn't matter of solving that equation for x.
02:02
So i'm going to start by multiplying by 61 .9.
02:13
I get 93, or i'm sorry, 96 .2545.
02:24
Equals x minus 43 .2 and then add 43 .2 to both sides.
02:37
And we find this value that we're looking for is equal to 139 .4545.
02:51
Now, it says enter your answer is a decimal accurate to one decimal place...