Objects that float on water have densities less than the density of water; those that do not float on water have densisties greater than the density of water:
Float on water: d < 0.0361 lb/in³ (where d denotes denisity)
If you think about it in a real life scenario, if one person does the job and then another person does the same job at the same speed wouldn't it be the same time? But if its not i think it would be 15 minutes because 45-30 = 15
