To whom would girls say hello? (Girls only)

Girls, would you ever say hello to a completely random guy and if you do, why? Is it because you like him or you want to be his friend? Would if say hello if his friends are near him or if your friends are with you? I am asking this because there is this girl who who ALWAYS says hello and talks with me whenever my friends aren't with me and her friends aren't with her (if her friends are next to her, she'll start talking to them). I hardly know this girl and I'm pretty sure she doesn't know me so why would she try and talk with me? Something else I noticed was that she was smiling the entire time when she was talking to me (then again, she smiles whenever she talks to anybody). Also this girl NEVER looks at me whenever we pass by each other in a hallway? I'll describe the girl to help you figure out why she might be doing this. She is smart and kind but isn't spontaneous or loud (she would never do anything to attart attention to herself). She is usually quiet and seems to ONLY start talks with her friends (I don't think she would start a talk with anybody who isn't her friend except me which I find weird).Also all of her friends are girls except one who is a guy. SO, why do you think she's trying to talk to me?
To whom would girls say hello? (Girls only)
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