Get the Paython tar and build and install.
sudo apt-get install libssl-dev openssl wget https://www.python.org/ftp/python/3.5.0/Python-3.5.0.tgz tar xzvf Python-3.5.0.tgz cd Python-3.5.0.tgz ./configure make sudo make install
Test the install
python3.5
if it is not linked, then do the following:
sudo ln -fs /opt/Python-3.5.0/Python /usr/bin/python3.5