9) Two homogeneous objects, made of two different materials, have the same volume, but the first weighs $242 \mathrm{~g}$ more than the second. Knowing that the material of the first object has a density of $8.9 \mathrm{~g} / \mathrm{cm}^{3}$ and the material of the second object has a density of $7.8 \mathrm{~g} / \mathrm{cm}^{3}$, what is the volume of each of the objects?
(A) $120 \mathrm{~cm}$
(B) $150 \mathrm{~cm}^{3}$
(C)
(D) $300 \mathrm{~cm}^{3}$
(E) the data provided are insufficient.
9) The answer is (C). Let $V$ be the unknown volume expressed in $\mathrm{cm}^{3}$, the weight of the first object is $8.9 V$, that of the second is $7.8 V$. Therefore, $8.9 V - 7.8 V = 242$, from which $V = 220 \mathrm{~cm}^{3}$.