Stumped... can someone derive a formula for this single vari

[AD1985]

You have 10 days of numbers that are averaged together (10 day avg). The most recent 3 days of numbers also averaged (3 day avg). The 3 day average is divided by the 10 day average to arrive at (3d/10d)

The oldest number in the series is dropped off and a new one, X, is added. X is the newest number and thus a part of both the day and 3 day average. The (3d/10d) remains the same. What is X?

I need to write a formula for this in excel! That means every computation on one side of the = sign, and I'm not even sure if Excel can take variables. I think the trick is figuring out the formula for the new 3d/10d, but not sure. Any ideas?




Thanks

 

[stapel]

You have 10 days of numbers that are averaged together (10 day avg). The most recent 3 days of numbers also averaged (3 day avg). The 3 day average is divided by the 10 day average to arrive at (3d/10d)

The oldest number in the series is dropped off and a new one, X, is added. X is the newest number and thus a part of both the day and 3 day average. The (3d/10d) remains the same. What is X?

What are your thoughts? What have you tried? How far did you get? Where are you stuck? :?:

I'm not even sure if Excel can take variables.

So you clicked on "Help" in Excel, typed "variables" in the "search" box, and got no results or advice...? This would seem to indicate that something is wrong with your installation of the program. While you're waiting for Excel to be re-installed or otherwise fixed, try studying any of the online articles available on this topic. :wink:

Eliz.

 

[Deleted member 4993]

You have 10 days of numbers that are averaged together (10 day avg). The most recent 3 days of numbers also averaged (3 day avg). The 3 day average is divided by the 10 day average to arrive at (3d/10d)

The oldest number in the series is dropped off and a new one, X, is added. X is the newest number and thus a part of both the day and 3 day average. The (3d/10d) remains the same. What is X?

I need to write a formula for this in excel! That means every computation on one side of the = sign, and I'm not even sure if Excel can take variables. I think the trick is figuring out the formula for the new 3d/10d, but not sure. Any ideas?




Thanks

If, as shown, all the numbers are given to you - then this is a simple algebra problem

add 2... 10 th number = M

add 9 th and 10 th number = N

The ratio of the averages = A

'X' comes in - 19 is bumped out.

Then

\(\displaystyle A \, = \, \frac{\frac{M+X}{10}}{\frac{N+X}{3}}\)

solve for 'X'.......

 

[AD1985]

Re:

So you clicked on "Help" in Excel, typed "variables" in the "search" box, and got no results or advice...? This would seem to indicate that something is wrong with your installation of the program. While you're waiting for Excel to be re-installed or otherwise fixed, try studying any of the online articles available on this topic. :wink:

Eliz.

This does not show how to enter variables into a formula, it makes a graph for variable costs. I'm still trying to figure out how to do this. Now that I have the equation (thanks!) I just need to figure out how to neter a variable into an equesiton. It looks like excel is not capable for that however.