Drop down list returns formulas

[AFC12]

Is it possible for a drop down list to return formulas?

I've created a drop down list for "Rate" and "labour & Materials". If I select "Rate" from the drop down list I would like to auto populate a cell on the same line using Iferror and Vlookups.
Subsequently if I select "labour & Materials" I would like the cell to carry out a calculation

[PaulM100]

you need a formula in that cell like: =if(a2="Rate",iferror(vlookup formula)),if(a2="labour and materials",your calculation,""))

[AFC12]

Thanks for the help