An iron ball 4 inches in diameter weighs 9 pounds. Find the Weight of an iron shell 2 inches thick whose external diameter is 20 inches.

Question

anonymous · Answer

First you need to find how much one cubic centimeter of iron weighs

anonymous · Answer

So you would set it up like$$\frac{ 4\pi(2)^2 }{ 9}$$

anonymous · Answer

to find lb/cubic inches

anonymous · Answer

and then the iron shell is a hemi sphere

anonymous · Answer

can you explain it step by step? I don't seem to get it. :/

anonymous · Answer

$$\frac{ area~of~sphere }{ weight~of~sphere }= Pounds~per~cubic~inch$$

anonymous · Answer

$$2\pi(2)^2=Cubic~inches~inside~of~hemisphere$$

anonymous · Answer

$$Pounds~per~cubic~inch*area~of~hemisphere=weight~of~hemisphere$$

anonymous · Answer

is it area or volume of the sphere? -.-