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I started off dumb on this one and the longer I stare at it the dumber I get.
I'm working out averages two different ways for the same set of figures and get two different answers:
[img] http://ubuntuone.com/0Oz7Xu2mdpCPpPaE7rjXsi [/img]
For the life of me I can't tell why the average of col C and the answer of Col B divided by Col C are different. And if some reason they should be different, which one is the right "average charge per mile"?
The 0.74 one.
The other one wrong because you're taking an average of an averages. I hate stats, and tbh this isn't even stats, it's accounting or finance or something equally dull and stupid. But basically the 0.86 is the average of what you pay on average per mile for a trip, rather then the average of charge per mile for all trips.
Suppose it depends what you want really, and how precise you want to be. Call it 80p?
Also, shouldn't that last line say average of column C?
Unless you've got loads of rounding errors..?
Are you meant to have 'sum Col A' in the first formula - as this has nothing to do with your calculation?
It's a bit like a rate issue. But basically, the .74 average is based on the toatl numenr of miles, i.e. The proper average. In this you have some averages, which extended for lots of miles and some which apply to only a small distance. The .74 takes this into account. The other average gives equal weight to every individaul average, regardless of how much it contributes to the overall.
E.g. If i run 100 metres in 18 seconds, but then take 7 minutes to run the next 1400, you would not work out my average speed by finding the middle of the two separate averages
You are being inconsistent.
The average should be 126.02/171 = 0.74 (The sum of column B divided by the sum of column A)
The average of Column C is the average of averages, but the miles travelled on each of the 5 trips were different, but in averaging them you are giving each trip equal weight. I doubt this is what figure you are after.
Total cost / Total miles will give you charge (cost) per mile
Are you meant to have 'sum Col A' in the first formula - as this has nothing to do with your calculation?
It's the column I've headed col A rather than the sheet col A, if that's what you mean?
I struggle with long sentences
All I know is that 5 and a 1/4 inches is statistically within the range of 'average'.
Thanks! I think I actually understand that now!