其它
\textbf{A stationery store owner calculated the mean and median price of all types of pen: 5 and 3, respectively. He plans to have a 20\% off sale. What are the new mean and median of pens in that store?} 
Overseas Competition->Knowledge Point->Calculation Modules
\textbf{If you times some number to the data set,~ the mean or median needs to be times with the same number. So for here, everything times with 0.8.} 