average formula, need it to change depending on number of years

[Badnames]

I have three years with a different value, year 1-3 are in cells R14-T14.

The values for years 1-3 are 20, 12, 6.

From a dropdown in C9 I'm selecting the number of months 12,24,36.

In cell p14, i want to have an average formula, that averages up to all three years depending on what I choose from the drop down.

So for 3 years, I'd get 12.6677777, for 2 16, and 1 20.

I initially thought an average with indirect, such as:

=average(r14:indirect("rc[2+($c$9/12)]",0)

I've been unlucky using an indirect though. Any thoughts on how I can have the formula shift depending on the years? I really don't want to use a long if.

 

[barry houdini]

Try using INDEX like this

=AVERAGE(R14:INDEX(R14:T14,C9/12))

 

[Badnames]

Awesome, it works. Don't know why i didn't think of an index.