[tex]\displaystyle\\
a)\\
0,(0003)=\frac{3}{9999}=\frac{1}{3333}\\\\
1,2(9)=\frac{129-12}{90}=\frac{117}{90}=\frac{13}{10}\\\\
3,70(2)=\frac{3702-370}{900}=\frac{3332}{900}=\frac{833}{225}\\\\
1,2(417)=\frac{12417-12}{9990}=\frac{12405}{9990}=\frac{827}{666}
[/tex]
[tex]\displaystyle\\
b)\\
0,02(03)=\frac{203-2}{9900}=\frac{201}{9900}=\frac{67}{3300}\\\\
10,3(27)=\frac{10327-103}{990}=\frac{568}{55}\\\\
11,47(3)=\frac{11473-1147}{900}=\frac{10326}{900}=\frac{1721}{150}\\\\
0,002(1)=\frac{21-2}{9000}=\frac{21-2}{9000}= \frac{19}{9000}
[/tex]