Referencing a Table

[PJ14]

Hi Guys,

I am stuck on something that I think you will all be able to help with. (I am not a newbie but by nowhere near an expe

I have attached the page I am working on.

The Formula is in B7.

The formula is: (I4 x Vapour Pressure-E4:E54 x B5 / 100) / (I3 +B6-D4:D54)*1000

Now the tricky part is that whatever the B6 value is, it will change what the value of for Vapour Pressure is. For example if B6 = 15(D19) then Vapour Pressure will equal 1.7056 (E19) making the formula:

(I4xE19xB5/100)/I3+B6)*100)

So the question is how do I make the equation work correctly?

I hope this makes sense and any help qould be much appreciated.

Thanks
Peter

[Glenn Kennedy]

Hi. If the temperature can be measured in decimals (e.g. 15.5), use this:
=SUM(I4*B5*VLOOKUP($B$6,$D$4:$F$54,3,TRUE)/100)/(I3+B6)*1000

it'll use the VP appropriate to the closest temperature. If the temperature will always be an integer, use this:

=SUM(I4*B5*VLOOKUP($B$6,$D$4:$F$54,3,FALSE)/100)/(I3+B6)*1000