Need way to self populate multiple cells based on selection from drop down with NUMBERS

This is what I need and what I already know: (Using Excel 2010)

1. Have drop down with fraction sizes
2. Depending on which fraction size is chosen, multiple cells will be populated with a corresponding decimal weight.
3. Need multiple cells to populate a set of data based on a single drop down menu.

For Example

If I select 3/8 from a drop down list in A1, then B1 automatically populates with a specific weight that is tied to 3/8
If I then select 1/2 from the same drop down in A1, then B1 would populate with a different weight that is tied to 1/2

I've been here: http://www.contextures.com/xldataval02.html

It helped me almost get there, but I want the B2 cell to SELF POPULATE with a single specific weight after I have made a selection in the drop down from A1. Also, these tips become more difficult when working with fractions and numbers and not words. I'm willing to hear any suggestions including formulas and vba codes. Also, If giving a formula, please explain each piece so I can potentially make changes or additions to the formula while still knowing what each piece means. THANK YOU.

welcome to the forum

perhaps it would be easier to help you if you uploaded a sample workbook, showing what data you are working with, a few examples of what your expected outcome would be, and how you would arrive at that (remove any confidential info if necessary).

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I have started by setting up named ranges on the ITEM sheet (you will need to complete them). Then I added a helper column in sheet1 J (you can hide this if you want) for use with the range names. then in D4, copied down, I used
=INDEX(INDIRECT(J4&1),MATCH(C4,INDIRECT(J4),0),2)

take a look atthe attached and see if it gives you what you want (so far) I see that you have info JOINT LENGTH sheet, but it looks incomplete - you can probably use the same method I just did, to pull in that info