Find nearest value

[I need help!!! via AccessMonster.com]

Hi I'm making a database and I need to find the nearest value to a number
from a seperate table. Heres an example:

I have the value 9.5 in my order form table and need to fin the nearest
value in a list of numbers I've got in a seperate table. I also need to put
the result in a seperate field in the first table.

E.g.
1st table 1st table 2nd table
Preferred Weight | Actual Weight /~/ List of Weights
9.5 ??? 9.874
5.623
8.769
9.215

Now I need to find the weight that is nearest to the Preferred weight from
the List of Weights and put the answer in the Actual Weight. as you can see
I'm not exactly the most experienced person with databases but I am trying
So any help will be appreciated. Thanks.

 

[I need help!!! via AccessMonster.com]

um sorry didn't realise it would move the numbers away from where i put
them so for my sake just imagine where they are supposed to be Cheers. I
still need help!!!