Ceramics constitute an artefact quite present in the history of humanity. One of its various properties is shrinkage (contraction), which consists of the evaporation of water existing in a ceramic set or block when subjected to a certain elevated temperature. This elevation of temperature, which occurs during the firing process, causes a reduction of up to 20\% in the linear dimensions of a piece. Suppose that a piece, when moulded in clay, had a rectangular base whose sides measured 30 cm and 15 cm. After firing, these sides were reduced by 20\%. In relation to the original area, the area of the base of this piece, after firing, was reduced by (A) $4\%$. (B) $20\%$. (C) $36\%$. (D) $64\%$. (E) $96\%$.
Ceramics constitute an artefact quite present in the history of humanity. One of its various properties is shrinkage (contraction), which consists of the evaporation of water existing in a ceramic set or block when subjected to a certain elevated temperature. This elevation of temperature, which occurs during the firing process, causes a reduction of up to 20\% in the linear dimensions of a piece.
Suppose that a piece, when moulded in clay, had a rectangular base whose sides measured 30 cm and 15 cm. After firing, these sides were reduced by 20\%.
In relation to the original area, the area of the base of this piece, after firing, was reduced by
(A) $4\%$.
(B) $20\%$.
(C) $36\%$.
(D) $64\%$.
(E) $96\%$.