At the beginning of the school year, $30\%$ of all students in Ms. Rodriguez's art class preferred "Painting" as their favorite medium, and $70\%$ preferred "Sculpture." At the end of the school year, $60\%$ preferred "Painting" and $40\%$ preferred "Sculpture." Altogether, $x\%$ of the students gave a different answer at the beginning and end of the school year. What is the difference between the maximum and the minimum possible values of $x$?