How to find where a package is installed by pacman?

I am not on my arch now to check, but I bet pacman -Ql boost-libs or pacman -Qk boost-libs will do the trick by providing you with the list of files installed by the package.

pacman -Q  boost-libs    #Display version
pacman -Ql boost-libs    #Display file list provided by local package
pacman -Qk boost-libs    #Check the local package database
pacman -Qo /path/to/file #Check if the file is owned by any package