'les coefficients sont en ligne 11
With [I15].Resize(100)
.Cells(1).FormulaArray = "=IF(ISTEXT(RC2),SUM(IF(ISNUMBER(RC3:RC7),RC3:RC7*R11C3:R11C7))/SUM(IF(ISNUMBER(RC3:RC7),R11C3:R11C7)),"""")"
.Cells(1).AutoFill .Cells
.Value = .Value 'supprime les formules
End With