Okay, my OPINION so don't bag on me...
If she is telling the truth about the studying then I would say YES SHE IS INTERESTED IN YOU
If she asked to "hang out" outside of where you and her usually socialize, then YES, she is interested in you because she asked to "hang out" besides at school or whatever, am i right? *raises eyebrow*
If she's not interested....
Yes she's trying to keep her distance by saying she's busy and doesn't want to go to the movies... but she still wants to be friends OR she is trying to turn you down lightly...
IF SHE'S not sure about your or doesn't trust you, she's just trying to get to know you better before drawing a conclusion, HOPE MY LITTLE EVALUATION OF DATA HELPED
"In the arithmetic of love, one plus one equals everything, and two minus one equals nothing."
-- Mignon McLaughlin