Percentage tolerances excel formula help please

Hello,

I am trying to create a table to calculate percentages and tolerance percentage. Here is my example.
Let's say I have a reference chart. This chart in column A4 to A14 will list number of load cells 1 to 10.
In B column cells B4 to B14 will display load cell weight values for each of the individual load cells.
Column C will show the weight percentage for each of the corresponding individual load cells.
Cell D4 will display total load cells combined weight.
Cell D5 will display average of load cells.
Also have to keep in mind that the number of load cells may vary between 4 and 10.
Here is where it gets tricky. Cell D6 is where load cell tolerance needs to be. So example is there is 8 load cells all are reading at 400. Therefore tolerance is 0%. Next example is load cell 1 is reading 359, load cell 2 is 632, load cell 3 384, load cell 4 is 135,load cell 5 is 508, load cell 6 is 832, load cell 7 is 543, load cell 8 623. What would the tolerance percentage be and how and what would be the formula to calculate result for cell D6.
Thank you very kindly for your help :)