# How to calculate average fleet age? URGENT

1. ## How to calculate average fleet age? URGENT

Hi everyone,
I need help with calculating the average fleet age. I have a number of cars for the years 2007-2016, and they are included in the age groups of cars less than 2 years, 2-5 years, 5-10 years and 10-20 years. I need an average age for every one year. Thank you in advance for your help.

I attach a data file.
average age of fleet.xlsx

2. ## Re: How to calculate average fleet age? URGENT

What excel version are you using. Your profile says 97-2003, but you attached an .xlsx....

What EXACTLY are the numbers that we are looking at? Why do the totals not add up??

3. ## Re: How to calculate average fleet age? URGENT

Some files in my PC,I have in MS 2010 some in MS 97-2003. Data are taken from EUROSTAT and I havenīt blown them yett...therefore some values are missing and also the total does not fit.
I guess that for 2013-2016 all the data is available, only the total must be adjusted.

4. ## Re: How to calculate average fleet age? URGENT

With a helper column (manually calculated), being the number of years in each range (e.g. 0-2 is 2; 2-5 is 3, etc) in L2 to L5.

With replacement of n/a with 0

With the assumption (there is no alterantive, I think) that the number of cars in each RANGE is evenly distributed amongst the number of years in that range: e.g. 100 cars in the 0-2 range is equivalent to 50 cars in each year

Use this array formula, copied across:

Formula:
`Please Login or Register  to view this content.`

I have included a "proof" from row 10 downwards (for my benefit as much as yours!!).

Array Formulae are a little different from ordinary formulae in that they MUST be confirmed in the FIRST CELL ONLY by pressing CTRL+SHIFT+ENTER to activate the array, not just ENTER. After that, the array can be dragged down as normal, to cover the desired range.

You will know the array is active when you see curly brackets { } - or "curly braces" for those of you in the USA, or "flower brackets" for those of you in India - appear around the outside of your formula. If you do not use CTRL+SHIFT+ENTER you will (almost always) get an error message or an incorrect answer. Press F2 on that cell and try again.

Don't type the curly brackets yourself - it won't work...

You may need ; as the separator instead of ,

5. ## Re: How to calculate average fleet age? URGENT

On reflection, since the number of old cars in the early years is not zero, but is unknown... it might be more valid to EXCLUDE them from the analysis altogether and use ONLY those ranges (i.e. up to 10 years) where you have a complete set of data.

But... you know why you want these numbers... so your own opinion is more important than mine!!

6. ## Re: How to calculate average fleet age? URGENT

I've just realised. It doesn't always work. The sample gicves the correct answer only by acident. It's PROBABLY OK for your numbers... but only probably. Back to the drawing board!!

7. ## Re: How to calculate average fleet age? URGENT

Purely by luck, the answers were correct, even though the formula was wrong!! It worked fine, providing that the estimated number of cars per year BETWEEN age groups ALWAYS FELL with incereasing age. In this case, it was the case... but it might not always be so. Two helpers, even though only one is used. the other is there to indicate the source of the numbers in the array constant ( the {0,2,5,10} towards the end of the formula) just in case your datasets don't always follow the same pattern.

The revised formua is longer (there may be a way to shorten it... but my head is now sore!!). It's still an array formula.

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