To install QT Creator on Mint 13-17 and Ubuntu 12-14 run the following from terminal as su / sudo
32 Bit Systems
wget download.qt-project.org/official_releases/qt/5.3/5.3.1/qt-opensource-linux-x86-5.3.1.run
chmod +x qt-opensource-linux-x86-5.3.1.run
./qt-opensource-linux-x86-5.3.1.run
Then follow the onscreen installation
64 Bit Systems
wget download.qt-project.org/official_releases/qt/5.3/5.3.1/qt-opensource-linux-x64-5.3.1.run
chmod +x qt-opensource-linux-x64-5.3.1.run
./qt-opensource-linux-x64-5.3.1.run
Then follow the onscreen installation
Depending on your system you may well need the following two dependencies too
apt-get install build-essential
apt-get install libx11-xcb-dev libglu1-mesa-dev libxrender-dev
