Answer:
Step-by-step explanation:
So first we set this problem up
3 Red + 7 Blue + 5 Green = 15 Total Marbles
The chances of picking a different coloured marble each time is the product of the probabilities of picking an individual colour.
Since we have 15 total marbles, therfore number of possible outcomes of picking a red marble is 3/15=1/5
Similarly, number of possible outcomes of picking a blue marble is 7/15
number of possible outcomes of picking a green marble is 5/15=1/3
Therefore, the probabilities of picking a different colour each time=(1/5) (7/15) (1/3)=7/225