Hi!

D1 = 0.62
E1 = 1

Array entered:

=SUM(LINEST(B1:B4, A1:A4)*D1:E1)

Returns: 13.648

???

Biff

"Mal" wrote in message
...
I am looking for a formula to include in a spreadsheet for the following:

I have two equal length columns of no more than 50 numbers.

Say:

A B
1.5 9.8
1 11.7
.5 14
0 16.7

I have two reference cells with values 1 and .62.

If I look up column A reference "1" the answer I am looking for in column
B is "11.7" which I can work out using the Lookup function.

With the second number .62, the answer I am looking for needs to be 13.724
which is the pro-rata difference between the values in A and B.

Any help would be appreciated.

Thanks,
Mal