Answer:
2 drums
Step-by-step explanation:
Given:
Length of dock = 20 ft
Width of dock = 3 ft
weight of dock = 500 lbs
Volume of plastic drum = 50 gallons
also,
1 gallon = 1 gallon = 0.0.0038 m³
or
50 gallons = 50 × 0.0038 = 0.189 m³
Now,
The dock will float If the upthrust provided by the barrels is equal to or greater than the weight of the dock i.e the volume of water displaces is equal to volume of the barrel.
therefore,
mass of the water displaced = volume of drum × Density of water
or
mass of the water displaced = 0.189 × 1000 = 189 kg
and,
1 kg = 2.20462 lbs
thus,
189 kg = 416.67318 lbs
therefore,
the number of drums required is = [tex]\frac{\textup{500}}{\textup{416.67}}[/tex]
or
the number of drums required = 1.199 ≈ 2 drums