What are the odds she's a virgin?

Not that I care that much cos Im falling for her but Im just wondering... she's 15. I'm 16. She says shes a virgin. My friend who knows her says shes had sex with 4 guys. She is very attractive and VERY flirtatious. Her parents are orthodox jewish and have strict rules but I can tell shes pretty rebellious. Im not jewish and shes my girl so... anyway Im just wondering. The way she carries herself... Im just not sure.