Hi,

I have two sets of numbers and I need to be able to interpolate very
accurately the numbers I dont know for the A column not al lof them
just say 680 for example. What would the corresponding B colum number
be?.

A
270
370
409
440
550
555
640 (new number in series)
740
850

B
411
288
264
236
210
205
XXX (Unknown)
153
131


I have tried linear regression and it doesent work, probably because
the second set of numbers decrease as the first set increase.

Any advice greatly appreciated.

Cheers,

Aaron.