Math tutor

I'm a senior in math, and recently, I was informed of a private tutoring opportunity for a local high school kid who needed helped with calculus. I've volunteered in the university's own tutoring lab that helps freshmen students with basic and advanced algebra, so I have some tutoring experience. The question is what are the usual rates for a private math tutor? I had originally thought of charging $10/hour and then decided on $15/hour.

Does anyone have any tips? What are the usual rates you've heard?

if its 4tran   $pi*9000