1. a bag contains 12 white counters, 7 black counters and
1 red counter.

a) if, when a counter is taken out, it is not replaced,
calculate the probability that:
i) the first counter is white,

ii) the second counter removed is red, given that the
first was black.

b) if, when a counter is picked, it is then put back in the
bag, how many attempts will be needed before it is
mathematically certain that a red counter will have been
picked out?