Math Is Fun Forum

jacton

Member

Registered: 2011-09-02

Posts: 3

Running Average totals

I need to work out the individual average of two sums, in percentage terms, then when the next figures arrive i need the individual average and also the total running average.

2 for 7 against. Whats the average percentage
7 for 3 against. I know this average is 70% and 30% but whats the running average when you add the for's together it equals 9 and the against equals 10 so what is the average in percentage terms.

My calculations then go on to
7 for 4 against
9 for 3 against
8 for 3 against

Can anybody help me with the formula for this.

Please

Bob

Administrator

Registered: 2010-06-20

Posts: 10,583

Re: Running Average totals

hi jacton,

I think I can make a formula for you but I'm still a bit confused about the data you have given.

First I thought these were betting odds but then I thought maybe team scores against opponents.

Please would you clear this up for me?  Where did the figures come from and what would you like to achieve with them?

Bob

ps.  I've got to take my laptop for a service later today, so, apologies if I cannot respond quickly.

Last edited by Bob (2011-09-02 19:14:10)

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

jacton

Member

Registered: 2011-09-02

Posts: 3

Re: Running Average totals

Yes they are football scores for and against. I understand that you add the for's together and then add the against but cannot seem to remember how to work out what the average is.

For example I know my totals are 33 for and 20 against. This is a total of 53 but what I need is the percentage of the 33 from the total of 53.

I am sure its a simple calculation but as you get older you rely on computers and forget your basic maths, I'm sure I used to be able to do this sort of calculation in my head but not anymore, so any help will be appreciated.

Thanks

Bob

Administrator

Registered: 2010-06-20

Posts: 10,583

Re: Running Average totals

hi jacton,

Thanks for clearing that up.

You need a running total of 'fors',say, F; a running total of 'againsts', say, A; and a running total of 'total goals', say, T.

Then percentage_for is given by

and percentage_against

So, for your figures we'd have

and

Notice that these add up to 100%.  That should always happen so it's a useful check on your calculations.

Then if the next game is for = 17 and against = 19

the new running totals are F = 33 + 17 = 50;    A = 20 + 19 = 39;    T = 53 + 36 = 89

so the new percentages are:

and

Hope that helps, 

Bob

Just got to back up my drive and I'm off to the computer shop now.  Back this evening ie GMT 2000 ish

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

jacton

Member

Registered: 2011-09-02

Posts: 3

Re: Running Average totals

Many thanks for your help perfect.

I have now put this into an excel formula so all I have to do is add the scores and the percentages are calculated for me.

Once again many thanks

Bob

Administrator

Registered: 2010-06-20

Posts: 10,583

Re: Running Average totals

hi jacton,

You're welcome.  Computer shop couldn't do 'til Tuesday so I'm back on line quicker than I thought.

I was going to suggest Excel, but it seems you are way ahead of me.

One final thought:

If you want ............  put in some figures, do a screen shot and post that.  I'll check I make it the same.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob