Total number of marbles = 10 + 20 + 30 = 60
Number of ways of drawing 5 marbles from 60 marbles = 60C5
(i) All the drawn marbles will be blue if we draw 5 marbles out of 20 blue marbles.
5 blue marbles can be drawn from 20 blue marbles in 205 ways.
∴ Probability that all marbles will be blue =20C5 / 60C5
(ii) Number of ways in which the drawn marble is not green =(20+10)5
∴ Probability that no marble is green = 30 / 605
Probability that at least one marble is green = 1 – 305 / 605