Sub q2a()
Dim MaPlage As Range, Cptlig As Long

Set MaPlage = ThisWorkbook.Worksheets("Feuil1").Cells(1, 1)
MaPlage.Offset(, 6).Value = "Moyenne T1-T4"
'Parcours la plage en ligne
For Cptlig = 1 To MaPlage.End(xlDown).Row - MaPlage.Row

    MaPlage.Offset(Cptlig, 6).FormulaLocal = "=Moyenne(" & MaPlage.Offset(Cptlig, 2).Resize(, 4).AddressLocal(True, True, xlR1C1) & ")"

Next Cptlig
End Sub

Sub q2b()
Dim MaPlage As Range, Cptlig As Long

Set MaPlage = ThisWorkbook.Worksheets("Feuil1").Cells(1, 1)
MaPlage.Offset(, 6).Value = "Moyenne T1-T4"
'Parcours la plage en ligne
For Cptlig = 1 To MaPlage.End(xlDown).Row - MaPlage.Row
'Complétez la ligne pour calculer la moyenne dans le programme
    MaPlage.Offset(Cptlig, 6).value = ????????

Next Cptlig
End Sub