First thing I'm gonna go over I'm gonna go over the mean and statistics we're gonna work in the central tendency portion of the book I'm gonna be on chapter three on page 137.
If you want to follow up in to speed things up a little bit I created a spreadsheet here if you look on page 137 of the textbook I have under it says the typical time is using collected data you compute the mean to discover the typical time it takes for you to get ready.
As two categories set up on page 137 you have you have days and I have all days which is ten days you can see here one to ten and then you have the times for each day that's a lined up as you see on page 137 and when the whole point of. This is I'm going to show you how to use the HP 10 b2 plus calculator.
I have I have a electronic version which is the same as the physical version of the calculator.
To get started what I want to do is I want to begin by I want to begin by starting out how to calculate the mean with this with this data in the spreadsheet using the HP calculator.
Switch over here is the calculator as you can see right next to it you can see the data points.
The first thing that we want to do if you have this calculator is the same thing physically you want to clear the memory.
How you clear the memory you just hit this hit the orange tab here and then you do the key here it's clear off.
You clear all and everything clear.
It's the first thing you want to do is just case you have something in memory.
And another thing is if you want to make sure that your decimal places I set up the two decimal places after the decimal.
And I say for instance if you had it at four like if the setup is for. All right, here then you want to set it to two what you do is you hit the you hit the orange key here orange then your display which is right here is the equal sign then on the on the keyboard and then you hit the number of decimals you want.
Here I want to and as you can see it changed from the four that they set up the tune.
There'll be a little more accurate and all round up for the things that you need.
Let's get started all the data points as you can see right here you have you have days one through ten and then you have the times you have thirty nine twenty nine forty three fifty two thirty nine forty four forty thirty one forty four and thirty five.
As it's the same setup as you see on page 137 of the statistics textbook and that's what statistics for managers using Microsoft Excel is the seventh edition as written by David Levine David Steven and Katherine Psychopaths.
If you don't have that textbook you should have it.
Anyway, let's get started.
I'm gonna start putting in data points using my my HP 10 B to calculate this.
First thing I want to do I want to put all the data points in all the times.
In order for me to get the mean.
What I'm going to do is and how do you do that which you can do you hit 39 as you see the first data point.
Yeah 39 you hit the input key and then you hit the Sigma plus.
So to add that right.
It's the data points again 839 input I don't know why I say mine is. All right, hold on. All right.
Let's try this again.
Let me it clear so. This is electronic copy we won't do that signore.
We start over again.
I'm gonna hit day 139 and put and a hat. Okay.
It's gonna be one data point.
The next day the point it's going to be 29 29 and put hmm.
I guess I could do it like this.
It's going to be thirty nine twenty nine the next data point day three is 43.
And your and your capital is it the physical calculator. This is a computer base.
What you're going to do is every time you hear the data point you're gonna hit the data point you can hit the input key right here then you're gonna hit the Sigma plus key that's gonna save in the memory or since. This is a since. This is a computer copy I have to do this way as I just found out.
So far it.
Move on to the fourth data point the fourth day the point here is 52.
Minute 52 we're going on to the next one well next day the point is 39 again does that right.
The six data point is 44 the seventh day the point is 40 the eighth data point is 31 the ninth data point is 9 the ninth day the point is 44 and the last data point the 10th day is 35.
Now that we have that in place to move this to the side and as you see it matches the data points here in the Excel spreadsheet.
Now that we have that in memory.
What we do is a I'm gonna clear my gonna clear my interface here.
I make it clear not clear all but just clear.
I have that I have my statistical data points saved.
What I want to do is I want to get the I want to get the mean.
How you normally get the mean you just you just add up all the data points and and that's we and then you divide it by how many data points there are which is in this case 10 is 10 data points 10 times. All right.
But with the calculator here with the HP calculator what you can do is to get the mean for all these data points you can do it fairly quickly and as you can see here you see the seven key right here the seven key as you see. This is the sign for the mean and statistics which is X line of X.
You have line of X.
For me to get the mean for all those data points what I do is I just hit this key here and then I hit the mean and then it gives me the mean of 39.6.
As you can see this the mean is thirty nine point six for that data set which if you look on page 137 you'll see when you do the calculations it comes up to the 396 divided by 10 and that's how I got the mean.
And if you want to check check it to make sure it's correct.
You hit clear. All right.
We're already know you want to do the sum of X here.
We got all these data points here and it's the statistical which is in the memory in your in your calculator that's the memory.
What you want to do is to verify that those statistical data points what you can do is you want to get a running total.
You can do what they call it right here there's a five keys the sum of X.
You hit the blue key right here you get the blue and and your calculator is going to be the blue up key over the up arrow. All right, just above the below the e right here.
You can hit that blue key and you say oh I want to do the sum of all points.
Which is the 5 key.
As you can see it's it's it matches what you see on page 137 it's a 396.
That's how you that's how you do the sum of all data points in your membrane on your calculator and then we know that there's ten data points but if you want to verify that right.
We could do hit clear you and they see how many data points you have you see this four key right here the four key you have this little blue in that means the number of points right that's a number of data points.
It's gonna match this number here which we know is 10.
When I hit the blue key blue a pair. Okay, let me hit that that tells me that it's ten data points right there as you can see in the calculator.
So to manually check it and make sure that the mean that we got was correct.
What you do is let me show you how to do this quick.
You want to do the sum of X.
You hit the blue arrow sum of x divided by blue key again and hit n for the data points they hit the equal sign and as you see it matches.
You know that you're correct that's one way of checking it but during an exam when you're using your calculator you wouldn't do it very quickly.
You try to avoid all of that.
Just make sure that you have it in memory and then and once you have it in memory you could you can get to mean very quickly by hitting the the orange key once you have all your data points then you hit the seventh key on your calculator we hit that and as you see it instantly calculates that for you yes.
Let me show you how to do variance standard deviation in the next video.