1) how old is your sister. 2) how old is he. how old is she. 3) how old are they. 4) how old are we. 5) I am in my fifties. this sentence is right or wrong please quick answer

All sentences are write. But you should start your sentence with a capital letter and put (?) instead of (.), as it's a question. So it will be written like this:- How old is your sister?

Correct

Right