Is it average?

Let $S$ be the sum of the expression, then we have:

$\begin{aligned} S & = \left \lfloor \frac{1}{2} \right \rfloor + \left \lceil \frac{1}{2} + \frac{1}{100} \right \rceil + \left \lfloor \frac{1}{2} + \frac{2}{100} \right \rfloor + \left \lceil \frac{1}{2} + \frac{3}{100} \right \rceil + ... + \left \lfloor \frac{1}{2} + \frac{298}{100} \right \rfloor + \left \lceil \frac{1}{2} + \frac{299}{100} \right \rceil \\ & = \sum_{k=0}^{149} \left \lfloor \frac{1}{2} + \frac{2k}{100} \right \rfloor + \sum_{k=0}^{149} \left \lceil \frac{1}{2} + \frac{2k+1}{100} \right \rceil \\ & = \sum_{k=0}^{24} \left \lfloor \frac{1}{2} + \frac{2k}{100} \right \rfloor + \sum_{k=25}^{74} \left \lfloor \frac{1}{2} + \frac{2k}{100} \right \rfloor + \sum_{k=75}^{124} \left \lfloor \frac{1}{2} + \frac{2k}{100} \right \rfloor + \sum_{k=125}^{149} \left \lfloor \frac{1}{2} + \frac{2k}{100} \right \rfloor \\ & \quad \quad + \sum_{k=0}^{24} \left \lceil \frac{1}{2} + \frac{2k+1}{100} \right \rceil + \sum_{k=25}^{74} \left \lceil \frac{1}{2} + \frac{2k+1}{100} \right \rceil + \sum_{k=75}^{124} \left \lceil \frac{1}{2} + \frac{2k+1}{100} \right \rceil + \sum_{k=125}^{149} \left \lceil \frac{1}{2} + \frac{2k+1}{100} \right \rceil \\ & = 25(0) + 50(1) + 50(2) + 25(3) + 25(1) + 50(2) + 50(3) + 25(4) \\ & = 0 + 50 + 100 + 75 + 25 + 100 + 150 + 100 \\ & = \boxed{600} \end{aligned}$