Hello there I hope you are having an great day :) If you select a marble without looking which colour are you less likely to pick, All together there is 10 marbles.
Orange : 2/10
Black : 2/10
Green : 5/10
Blue: 1/10
The less Colour is Blue as there is only 1 Marble so it probably the less likely to be picked.
Hopefully that helps you :)