Answer:
V’/V= 1.05
Explanation:
The density is defined with the ratio of the mass to the volume, for the fish with the collapsed sack
ρ₁ = m / V
The density of the fish with the bag full of air is
ρ₂ = m / V’
For the fish to float if it exerts its density must be exactly equal to that of the surrounding water
We clear the mass and match
m = ρ1 V = ρ2 V'
ρ₁ V = ρ₂ V’
V ’/ V = ρ₁ / ρ₂
V ’/ V = 1.05 / 1
V ’= 1.05 V
This is that the fish should increase its volume by 5%