# Difference between revisions of "2007 AMC 12A Problems/Problem 2"

## Problem

An aquarium has a rectangular base that measures 100 cm by 40 cm and has a height of 50 cm. It is filled with water to a height of 40 cm. A brick with a rectangular base that measures 40 cm by 20 cm and a height of 10 cm is placed in the aquarium. By how many centimeters does the water rise?

$\mathrm{(A)}\ 0.5\qquad \mathrm{(B)}\ 1\qquad \mathrm{(C)}\ 1.5\qquad \mathrm{(D)}\ 2\qquad \mathrm{(E)}\ 2.5$

## Solution

The brick has volume 8000. The base of the aquarium has area 4000. For every inch, the water rises, the volume increases by 4000 cm$^2$; therefore, when the volume increases by 8000 cm$^3$, the water level rises 2$cm$\Rightarrow\fbox{D}\$