N Harkawat wrote...
=AVERAGE(IF(A1:A6<0,(B1:B6)*(A1:A6)))
array entered (ctrl+shift+enter)
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This is wrong. Given 1 and 9 in A1 and A2 with A3:A6 blank, 1 and 2 in
B1 and B2, B3:B6 irrelevant. The weighted average of 1 and 2 with
respective weights 1 and 9 should be 1.9 [(1 * 1 + 9 * 2) / (1 + 9)].
The formula above gives 9.5. Do you know what a weighted average is?