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The wooden blocks are all floating, indicating that the buoyancy of the liquid in 2 is equal:

Then:

ρ water *g*V water = block gravity = ρ * g * v.

Namely: ρ water *4/5=ρ*2/3.

Liquid density ρ = ρ water * 6/5 =1.2 *1g/cm3 =1.2g/cm3 =1200kg/m3.