She is interested . . . . . . . . drawing and painting?

'Interested in' is used to indicate the interest (or eagerness) of someone in the subject they want to know more about or the action they wish to perform. The preposition of location or time 'in' functions to indicate a state of being that someone is metaphorically 'inside of.' Less often, we can use the expression 'interested to' followed by a verb of perception. 'Interested on' is never correct.