A cubical box is divided into four identical chambers that can hold one ball each. In how manyways can one fill the box with 3 blue balls, 3 red balls and 3 green balls?
Students attend our lectures, not because the mathematics we teach ‘makes lots of fun’ for us, but because they believe they can learn some essential knowledge from us. And each of our young students has only one life to live. We should therefore be a