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 20C5 ways
∴ Probability that all marbles will be blue =20C560C5
(ii) Number of ways in which the drawn marble is not green =(20+10)C5=30C5
⇒ Probability that no marble is green =30C560C5
∴ Probability that at least one marble is green =1−30C560C5