We can use a simple equation to solve this problem.
d = m/v
Where d is the density, m is the mass and v is the volume.
d = ?
m = 87.47 mg = 87.47 x 10⁻³ g
v = 0.03 mL
By applying the equation,
d = 87.47 x 10⁻³ g
/ 0.03 mL
d = 2.92 g/mL
Hence, the density of the mixture is 2.92 g/mL.
150/30 = 5
HF1 20/2 = 10
HF2 10/2 = 5
HF3 5/2 = 2.5
HF4 2.5/2 = 1.25
HF5 1.25/2 = 0.625
Answer: 0.63g