Marie does three equally time-consuming tasks in a row without taking breaks. She begins the first task at 1:00 PM and finishes the second task at 2:40 PM. When does she finish the third task?
$\textbf{(A)}\; \text{3:10 PM} \qquad\textbf{(B)}\; \text{3:30 PM} \qquad\textbf{(C)}\; \text{4:00 PM} \qquad\textbf{(D)}\; \text{4:10 PM} \qquad\textbf{(E)}\; \text{4:30 PM}$
The first two tasks took $\text{2:40 PM}-\text{1:00 PM}=100$ minutes. Thus, each task takes $100\div 2=50$ minutes. So the third task finishes at $\text{2:40 PM}+50$ minutes $=\fbox{\textbf{(B)}\; \text{3:30 PM}}$.