In the fall of 1996, a total of 800 students participated in an annual school clean-up day.  The organizers of the event expect that in each of the years 1997, 1998, and 1999, participation will increase by 50% over the previous year.  The number of participants the organizers will expect in the fall of 1999 is
$\text{(A)}\ 1200 \qquad \text{(B)}\ 1500 \qquad \text{(C)}\ 2000 \qquad \text{(D)}\ 2400 \qquad \text{(E)}\ 2700$
If the participation increases by $50\%$, then it is the same as saying participation is multipled by a factor of $100\% + 50\% = 1 + 0.5 = 1.5$.
In 1997, participation will be $800 \cdot 1.5 = 1200$.
In 1998, participation will be $1200 \cdot 1.5 = 1800$
In 1999, participation will be $1800 \cdot 1.5 = 2700$, giving an answer of $\boxed{E}$.