Question

An urn contains 5 red marbles, 4 black marbles and 3 white marbles. Then the number of ways in which 4 marbles can be drawn so that at the most three of them are red is ....

Answer 1

The question does not mention that whether same coloured marbles are distinct or identical. So, assuming they are distinct our required answer = ¹²C₄ – ⁵C₄ = 490 And, if same coloured marbles are identical then required answer = (2 + 3 + 4 + 4) = 13

Answer 2

5R + 4B + 3W