A basket contains 3 red balls 5 blue balls and 7 green balls. Two balls are picked one after the other without replacement find the probability that. (a) Both are red. (b) First is blue, the other is green. (c) One is blue, the other is green. (d) Both are of different colours. (e) They are of the same colours.
Just keep in mind the first time you pick you have 15 in the basket.
The second time you have 14.
So for example to get two red:
first pick
2/15
second pick 14 balls, one of which is red so1/14
so
2/15 * 1/14 = 1 / (15*7) = 1 / 105