STORE average speed for every 5 min

[JuAn2226]

hi this my code

Private Sub Form_Load()
car_count = 0
Cumulative_Speed = 0
End Sub
 
      Private Sub Timer1_Timer()
 
      Dim tmpNumber As Integer
 
      Dim i As Integer
      Dim Counter As Integer
      Timer1.Enabled = False    'stop timing while storing number
      Counter = 0
 
      Randomize
 
      lbltmpNumber = Int(Rnd() * 15) + 1
 
      'check if this number already exist
 
For i = 0 To 9
 
        If lblCar(i) = lbltmpNumber And lblEnd(i) = "" Then
 
            'the number exist -> do not store it
            EndTime = Now
            lblEnd(i).Caption = Format(EndTime, "hh:mm:ss")
            StartTime = lblTime(i)
            Timeduration = (((DatePart("h", EndTime) - DatePart("h", StartTime)) * 3600) + ((DatePart("n", EndTime) - DatePart("n", StartTime)) * 60) + (DatePart("s", EndTime)) - DatePart("s", StartTime))
            lblDuration(i).Caption = "" & Timeduration
 
            ' Count number of car which succesfully pass through reader 2
 
            car_count = car_count + 1
            lblNum.Caption = car_count
 
            ' Call a function to calculate speed
 
            S = Speed()
            lblSpeed(i).Caption = S
            lblSpeed(i).Caption = Format(S, "###.00")
 
            ' Calculate the Average Speed
 
            Cumulative_Speed = Cumulative_Speed + S
 
            lblAverage.Caption = Format(Cumulative_Speed / car_count, "###.00")
 
            Timer1.Enabled = True
 
Exit For
            ElseIf lblCar(i) = lbltmpNumber Then
 
            Timer1.Enabled = True
 
Exit For
          End If
Next
 
      'If this number does not exist -> store in Number Array
 
      If Timer1.Enabled = False Then
      lblCar(Index).Caption = lbltmpNumber  'store the number
      StartTime = Now
      lblTime(Index).Caption = Format(StartTime, "hh:mm:ss")  'store the time
      Index = Index + 1
 
 
       End If
 
      If Index = 10 Then   'stop after stored 10 number
 
       Timer1.Enabled = False
 
 
      Else  'do not reach 10
      Timer1.Enabled = True    'continue storing
 
      End If
 
      End Sub
 
 
Private Function Speed()
 
Speed = (100 / Timeduration) * (1000 / 3600)
End Function
 

My question here is how i modify my code to take total average speed for every 5 min.that means how to make car array reset and store the average then again display random number until 10 then store average n again an again until it 5 min. in 5 min all this array need to be sum and display the total average .