An urn contains 6 red chips numbered 1, 2, 3, 4, 5 and 6 and 4 blue chips numbered 1, 2, 3 and 4. Two chips are drawn at random one after the other and without replacement. What is the probability...

An urn contains 6 red chips numbered 1, 2, 3, 4, 5 and 6 and 4 blue chips numbered 1, 2, 3 and 4. Two chips are drawn at random one after the other and without replacement. What is the probability that their sum will be a) 10 b) at least 6 c) at most 8 d) an even number?