How much to charge for tutoring?

<p>Hi i am a second semester college freshman and i agreed to be a personal tutor for another girl for college physics I and calculus 2.</p>

<p>if i have never tutored math/science before, how much should i plan on charging per subject? i received an A+ in both classes so i feel that i have a good grasp of the material. the college tutorial cntr pays $8.50 to new tutors so i would at least like a bit more than that since im doing a personal gig. would $15/hr be too steep?
many thanks! </p>