Answer:
8.7 m
Explanation:
The pressure due to the mercury of height h = 64 cm = 0.64 m is
P = ρ₁gh₁ where ρ₁ = density of mercury = 13600 kg/m³
P = 13600 kg/m³ × 9.8 m/s² × 0.64 m = 85299.2 Pa
Since this is the same pressure for the water,
P = ρ₂gh₂ where ρ₂ = density of water = 1000 kg/m³ and h₂ = height of water
h₂ = P/ρ₂g = 85299.2 Pa/(1000 kg/m³ × 9.8 m/s²) = 85299.2 Pa/9800 kg/m ²s² = 8.7 m