Here is a really easy way to install the latest version of Python on Linux Mint. This is not my creation, I got the info from the following site:
$ sudo apt-get install libssl-dev openssl
$ cd /opt
$ wget python.org/ftp/python/3.4.1/Python-3.4.1.tgz
$ tar -xzvf Python-3.4.1.tgz
$ cd Python-3.4.1/
$ ./configure
$ make
$ sudo make install
The easiest way to make Python 3.4.1 as default is to symlink it:
$ sudo ln -fs /opt/Python-3.4.1/python /usr/bin/python