Question

A bag contains 6 red marbles and 3 yellow marbles. You are asked to draw 3 marbles from the bag without replacement. In how many ways can you draw 2 reds and 1 yellow?

Answer 1

ways of selecting RRY = 6 x 5 x 3 = 90

but RRY can be rearranged in 3!/2! ways ( because in RRY there are 3elements with 2repeats )

so total ways = 90x3 = 270