How to install old version of mongodb?
You have to add the repo list 

sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 7F0CEB10  
echo 'deb http://downloads-distro.mongodb.org/repo/ubuntu-upstart dist 10gen' | sudo tee /etc/apt/sources.list.d/mongodb.list
sudo apt-get update


Then re-run  sudo apt-get install mongodb=2.2.7

That should work. The repo list file was the differentiating step which you've missed