MSV 9: Do we divide by n or n-1?

The definition of 'variance' is always a hard thing to tackle.
There is going to be a certain amount of messiness in any explanation,
especially when books and calculators never seem to agree.
This spreadsheet and accompanying notes hope to make this topic as clear as possible
whilst remaining at the right level for AS students. The MEI definitions are followed here.

msv-9.pdf - The Notes

msv-9.xlsm - The Spreadsheet