This makes me wonder how did Sumi and yuyuko manage to score on their test too?... unless they manage to complete their tests earlier?
Sumi probably ditched or at least did okay on it. She's not a complete baka like some of the other characters we've seen so far but she isn't a true genius like Nitori so it's safe to assume her grade was passing(or at least close to it.) As for Yuyuko... I think we can refer to Steak for that answer.