I tried Martins way which gave me the correct answer, then i read about
forecast and gave that a go too. Thankyou, now i know two ways of doing it.

"Gary''s Student" wrote:

Since y=.277 we know that x is somewhere between 1.0 and 1.5

Read about the FORECAST() function in Excel Help. It does a great job of
interpolating between two points.
--
Gary's Student


"Moni" wrote:

I have 2 columns of data eg.

X Y I want to find an unknown x-value from a y-value of
0.277.
How do i use excel to plot this on a scattergraph?
0 0 Please help!
0.5 0.128
1.0 0.260
1.5 0.389
2.0 0.523
2.5 0.637