A box contains six red pens and three blue pens.

(a) A pen is selected at random, the colour is noted and the pen is returned to the box. This procedure is performed a second, then a third time. Find the probability of obtaining (i) three red pens, (ii) two red pens and one blue pen, in any order, (iii) more than one blue pen.

(b) Repeat

(a) but this time find the probabilities if, at each selection, the pen is not returned to the box.