To solve this question, we have to first consider the formula of density, defined as the mass per unit volume of a substance:
ρ = m/V
m=ρ
VWhere: ρ=density, m=mass, V=volume
We are already given the density of 850 kg/m^3, but how do we figure out volume? It’s pretty simple if we picture the oil tank as simply a cuboid. Since we know that a liquid like oil tends to take the dimensions of whatever container its in, the volume of oil will be equal to the volume of the cuboid it shapes itself as:
V = l.b.h = 2.4 . 1.5 . 1.5 = 5.4 m3
Therefore, the mass is:
m = 850 . 5.4 = 4590 kg
m=ρV