Thread: question about standard deviation

hello. recently i am doing a maths coursework. i am sampling a list of students, which i have randomly selected.

i recently done standard deviation. when i do standard deviation by hand using the forumula i end up with a different results compared to the one i end up with when using excel (its normally 1 number higher on excel). why is this?

please can someone tell why this is?

Standard dev has one formula that uses n in the denom and another that uses n-1
Excel is using a formula with a different denom.