Answer
See below
Work Step by Step
The margin of error formula is $M=\pm \frac{1}{\sqrt n}$
Find $n=\frac{1}{m^2}\\ \rightarrow n=\pm \frac{1}{(\pm 0.02)^2}=2500$
Hence, $M=\pm 0.02$
Since the interval is $[49,51]$, we may not know whether the exact percentage is higher than 50.