(a) An urn contains four $10 coins, six $5 coins and two $1 coins. Two coins are taken at random from the urn without replacement. What is the probability that both coins are of the same type?

(b) A box contains m white balls numbered 1 through m and m black balls numbered 1 through m.

If two balls are to be drawn at random without replacement, what is the probability that both balls will be of the same colour or have the same number? (Your answer should be in terms of m)