Access to Excel, calculate using imported data, then update original table (not append)

[aneer miss]

Hello all

Would someone please care to point me in the right direction (via past threads) on how to:

Access to Excel, calculate using imported data, then update original table (not append).

Actually, to be more specific - here is my situation:

I have already imported data to Excel from an Access database. Then I perform calculations in Excel on the relative fields that were imported, to produce one more field named RAT(relatiive to original table). After calculating this field I would like to import that new field into the original Access table (NOT appending new data to that original table).

I am a beginner (to VBA code), but can navigate my way around an Access db as well as MS Excel.

Could I get some directions please?

To complicate the situation even further, each date (a field) has around 100 records, so all those calculations need to be perfomed then the RAT field has to be imported to Access, THEN the next set of calculations for RAT use that field (RAT) to do its set of calculations, THEN this field has to be imported to Access etc. etc.

Being my first post, I probably haven't explained myself too well, but any ideas would be greatly appreciated.