An urn contains 6 white, 4 black and 5 red balls. Three balls are drawn successively without replacement. Answer all parts.
a. (i) Find the probability that the first ball drawn is white, the second is black and the third is red.
b. (ii) Determine the probability that the three balls drawn are all of different colours.
c. (iii) Calculate the probability that exactly two of the three balls are of the same colour and the remaining ball is of a different colour.