I want to calculate a mean and a variance, but when mean() is called
there is a type mismatch. why?

Function Mean(arr As Range)
Dim Sum As Single
Dim i As Integer

Sum = 0
For i = 1 To ran.Rows.Count
Sum = Sum + ran.Cells(1, i)
Next i

Mean = Sum / ran.Rows.Count
End Function

Function StdDev(arr As Range)
Dim i As Integer
Dim avg As Single, SumSq As Single

avg = Mean(arr)
For i = 1 To ran.Rows.Count
SumSq = SumSq + (ran.Cells(1, i) - avg) ^ 2
Next i

StdDev = Sqr(SumSq / (ran.Rows.Count - 1))
End Function

Sub MeanVar()

Dim ran As Range
Dim s, Mean, var, num As Integer


Set ran = Application.InputBox("in which range is the variable",
Type:=8)

M = Mean(ran)
s = StdDev(ran)

ran.Offset(1) = Mean
ran.Offset(2) = s

End Sub