to convert any decimal to a fraction, we simply use "as many zeros on the denominator as there are decimals, and lose the dot above", so 4.875 has three decimals, so let's put three zeros below it then.
[tex] \bf 4.\underline{875}\implies \cfrac{4875}{1\underline{000}}\implies \stackrel{simplified}{\cfrac{39}{8}}\implies 4\frac{7}{8} [/tex]