Subject: How does sound travel faster in a less dense medium and fastest in solids?

I was teaching the section on sound travel and the question arose that it 
seems contradictory that sound would travel faster through a less dense medium 
(like iron versus gold) and at the same time travel fastest through a solid as 
opposed to a gas because a solid is more dense than a gas. Does it have to do 
with longitudinal waves?

Re: How does sound travel faster in a less dense medium and fastest in solids?