This question is from probability chapter class 10th ncert/icse both boards included in this question A bag is given which contains 10 red, 5 blue and 7 green balls. When a ball is drawn at random. You have to find the probability of this ball being not a blue ball. Here i am not able to understand how can find the probability of not a blue ball. Do i have to find the probability of other remaining balls i am not sure.