How likely is it that a girl will become pregnant if the guy finished inside her and the condom was ripped?

The possibility is high. Try using a latex condom. the non-latex sometimes break easy. After you ejaculate you should hold on to the condom until you pull out, so the sperm doesn't leak out of the condom. Also, you should use Vaginal Contraceptive Foam with a condom as a back up. Or some condoms have spermicide in them. Ovulatin usually is 12 to 16 days before the period.

AnswerIts possible but there has to be eggs to fertilize, so figure out if she was ovulating. You can get an ovulation test or try to figure it on your own. A girl ovulates with in 10/14 days after the first day of her last period.