New battery not giving enough charge

Hi,

just purchased a new dell battery as my previous battery started swelling. New one is 97whr while my old one was 84whr. Local dell service guy told me it should give me 12hr, as my old battery was giving approx 6/7 hour when new. Battery health is showing 96% when first installed two days later after two full charge discharge cycle it’s showing 93%. Also it has only give LB 4/5 hour charge.

my question is

1) how do I know if it is pre-used battery and not a brand new,

2) also what should I expect on length of charge.. 12hr seems too optimistic and current 4/5hr seems low for brand new battery

3) how do I check warranties etc? Dell service guy mentioned 6 month warranty 

thanks

bhavin