Please help me thank you

The probability of picking a green marble would be 4/20 and then another green marble but not putting the first one back would be 3/19.
it would be 4/20 because their are only 4 green and if you add up all the marbles together you get 20.
it would be 3/19 because the first time you got a green but didn’t add it back so you have to subtract one from the green leaving you with only 3 greens making their only be 19 to pick out of.

hope this was correct & helped you out

The answer would be 13.5 minutes.