Tonks's age/ ages in general

[Rachel Wells]

No: HPFGUIDX 70278

With regard to Tonks leaving Hogwarts at 17, it is actually more 
likely that she left, and most students, leave Hogwarts at 18. Harry 
is one of the youngest in his year, because he has a July birthday, 
and so starts, for example, 5th year, aged 15. He will only turn 16 
in the Summer holidays after Oop, but, most students would have 
turned 16 during the 5th year, some even in September at the 
beginning of the year. It kind of confuses things that JKR has made 
it so that Harry is one of the youngest in his year!