there is a 50:50 chance of getting a red bead from the bag, there is 1 in 6 chance of picking out a blue bead from the bag, there is a 1/4 chance of picking out a green bead from the bag, it is impossible to pick out a yellow bead from the bag, there is 1 in 12 chance of picking out a black bead from the bag, how many of each of each colour are there?