What we'll do:
A method to find whether an object will float or sink in a liquid is to find it's specific gravity with respect to the liquid, The Specific Gravity tells us the percentage of object's mass which will be submerged in water
Finding the Specific Gravity:
Density of Box:
Density = Mass / Volume
Density = 80 grams / 78 cm³
Density = 1.02 grams/cm³
Specific Gravity of Box with respect to water:
Specific Gravity = Density of Box / Density of Water
we know that density of water is 1 gm/cm³, plugging the values
Specific Gravity = 1.02 / 1
Specific Gravity = 1.02
Hence, 102% of the object will be under water
Q. but I've only heard about 100% of something, how can something be more than 100%?
A. The answer is that the extra 2% over the 100% is providing to the object being even deeper underwater