Help with analysing data

[DebbyG]

I am trying to get my brain working today, but to no avail.

I need to analyse the below type of data to show various scenarios

A1 - No of letters
B1 - Qty/Mailing
C1 - No of Mailings is reflecting A1/B1

I can manage thus far!!!

A1 & B1 are likely to increase but not decrease in number

D1 is the maximum time it takes to complete A1 and cannot increase, even if A1 increases.

What I would like is some a form which takes all of the above equasions into account and tells me how many weeks it will take to process 5000 letters as a single or stages mailing, showing a message box, or similar if the completion time calculates to be over the maximum time allowed.

(A1) (B1) (C1) D1
No Letters Qty/Mailing No. Mailings Max Completion
[b1/a1] Time
2500 1000 2.50 20
6000 1000 6.00 22
3000 1500 2.00 22
3000 1000 3.00 22
3000 1800 1.67 22

I'm not sure if I've explained this very clearly.

Any help greatly appreciated.

Thanks

 

[BrianB]

Calculate the amount of time it takes to process 1 letter:-
=Time Taken divided by number of letters processed in that time

Calculate how long a certain number of letters will take :-
Number of letters to process times the result from above.