3.28 ft3 is the answer. I need solution

2) A cylindrical drum has a diameter of 2 feet and is 3 ft long. It weighs 30 lb, when it is empty. You need to add aluminum weights in the drum so that it neutrally buoyant in fresh water (that is, it will neither rise nor sink when it is totally submerged). Aluminum has a specific weight of 0.1 lb, in'. What volume of aluminum will you need to add? (3.23 ft)