Chapter 11 Data Analysis and Statistics - 11.4 Select and Draw Conclusions from Samples - Guided Practice for Examples 4 and 5 - Page 769: 3

See below.

a) Hence here the margin of error is: $\pm\frac{1}{\sqrt {1202}}\cdot 100\%\approx\pm2.88\%$ b) If the margin of error is $\pm2\%$, then our equation is: $\pm\frac{1}{\sqrt n}\cdot 100\%=\pm2\%=\pm0.02\\\frac{1}{\sqrt n}=0.02\\50=\sqrt{n}\\n=2500$. Thus $2500$ people would have to be surveyed.