Right Circular Cylinder problem...

1.) Find the waste in making the largest possible cylindrical rod from a bar of iron 3ft long which has a cross section whose diagonal is 6 inches.

2.) A certain factory manufactures tin cans. It received an order for 10,000 cylindrical tin cans of height 5 inches and diameter 3 inches. How many square feet of tin did this order require if 7 sq. in. are allowed for waste and seams in each can.

3.) A circular oak table top is 4ft. in diameter and 3/4 inches thick. How heavy is it if oak weighs 47 lb. per cu. ft.?