The histogram shows the time, in minutes, that $40$ customers waited at a counter. The classes are $0$ to $5$, $5$ to $10$, $10$ to $15$, $15$ to $20$ and $20$ to $25$. In which class does the median waiting time lie?

Fig. 1: A histogram with five bars of width 5 for the time in minutes that 40 customers waited at a counter. The bars start at 0, 5, 10, 15 and 20 and have heights 4, 12, 14, 7 and 3. The tallest bar is over the class 10 to 15.