The perimeter of a rectangular metal plate is 15 cm. Find the length of the rectangular plate (in decimals) whose width is 228 cm. Use estimation in tenths place.

The Solution.
Representing the problem in a diagram, we have
By formula,
[tex]P=2(L+W)[/tex]In this case,
[tex]P=15\operatorname{cm},L=?,W=\frac{22}{8}cm[/tex]Substituting these values in the formula above, we get
[tex]15=2(L+\frac{22}{8})[/tex]Clearing the bracket, we get
[tex]15=2L+(2\times\frac{22}{8})[/tex][tex]\begin{gathered} 15=2L+\frac{11}{2} \\ \\ 15=2L+5.5 \end{gathered}[/tex][tex]\begin{gathered} 15-5.5=2L \\ 9.5=2L \end{gathered}[/tex]Dividing both sides by 2, we get
[tex]L=\frac{9.5}{2}=4.75\approx4.8\operatorname{cm}[/tex]Therefore, the correct answer is option C.