Assuming your values are in cell A1 through A8 and the threshold is in
G1, try the following array formula which will return the place in the
array (in your example, 4). Commit the formula by pressing
Ctrl-Shift-Enter. If you want the value (45.61) instead of the
position, remove the Match( and the ,A1:A8) at the tail end of the
formula.

=MATCH(MIN(IF($G$1A1:A8,"",A1:A8-$G$1))+$G$1,A1:A8)

- John
www.JohnMichl.com