Quick, quick - need urgent help with whose/who's

[Lindenlass]

How are they used?

Proof-reading a friend's essay and can't for the life of me access that part of my brain!

e.g. 50% of the 70 men who's/whose hair had fallen out...

who's is an abbreviation of who is.

whose..., isn't

You need whose.

whose.

who's means who is.

who's is short for who is
whose is possession

at leatst I think its that straightforward. Someone will no doubt be along to correct me!

Thank you - that was my gut feeling, but you know when you change something and then go 'hang on...is that right? '?