Out of which box?
I'll answer for Box 1 and Box 2.
So in Box 1, you have 4 + 7 = 11 marbles in total.
Probability of drawing first marble green.
4 (green marbles) / 11 (marbles in total.
Probability of drawing second marble green:
Assuming you already drew a green marble, there's one less green marble, and one less marble in total:
3 / 10.
So the probability of drawing 2 green marbles in Box 1 is:
4 / 11 * 3/10 (since they're independent events) = 12/110 = 6/55
Probability of drawing 2 green marbles in Box 1 is: 6/55.
_______________________________
Now let's move on to Box 2:
You have 4 + 5 = 9 marbles in total.
Probability of drawing first marble green:
4 / 9.
Probability of drawing second marble green:
3/8
Multiply them since they're independent events:
4/9 * 3/8 = 12/72 = 6/36 = 1/6.
Probability of drawing 2 green marbles in Box 2 is 1/6.
