Ten students compared the amount (in dollars) they spent on books each week. The box plot shows the results. The median amount they spent each week is ____ ($20,$30,$40,$50) . The difference of the first and third quartiles of the data set is ____ ($15,$30,$45,$60).

Ten students compared the amount in dollars they spent on books each week The box plot shows the results The median amount they spent each week is 20304050 The class=