How do you make drop down items refer to specific array data?

[kanin247]

When using a drop down menu, how do you make the users selected choice refer to specific data in an array and use this data in an equation?

i.e.
Select Type (drop down menu)
- acsr 1351
- al 477
- cu '1/0'

Array [X,Y,Z]
[0.0803,0.369,0.0838] //data for acsr 1351
[0.0829,0.378,0.0855] //data for al 477
[0.1128,0.389,0.0890] //data for cu '1/0'

Equation
XF=Y*100/33

So, when the user selects a type, the values for that type are used in the equation.