How can one check which version of specific emacs package is being loaded

[Nobuko Three]

I installed the latest version of the Emacs package org-mode manually on my
Ubuntu machine. I didn't edit Makefile because I don't know how to do it, so
I believe there are two org-mode files on my machine: one is Emacs built-in
old version (Emacs is installed from Synaptic), another is the manually
installed new version. How can I check which one is being loaded?

Actually I added the following line to org.el before installing it.

(setq my-org-mode-version-is 625)

But something tells me my trick must be unnecessary. (This trick told me the
new version of org-mode is being loaded)

On the other hand, I also installed the latest reftex 4.33 package.  But
when do M-x find-library RET reftex RET, I get the old 4.31 version of the
file and when I evaluate the variable reftex-version, it says version 4.31,
the old version. But some behavior of reftex changed after I installed the
latest version. 

How can I make sure that the old version of a specific package not be
loaded? And what is the reliable way to verify it?
-- 
View this message in context: 
http://www.nabble.com/How-can-one-check-which-version-of-specific-emacs-package-is-being-loaded-tp23079431p23079431.html
Sent from the Emacs - Help mailing list archive at Nabble.com.