A bag contains 3 red balls, 5 black balls and 4 white balls. A ball is drawn at random from the bag. What is the probability that the ball drawn is :
(a) white?
(b) red?
(c) black?
(d) not red?
GIVEN: A bag contains 3 red, 5 black and 4 white balls
TO FIND: Probability of getting a
(i) White ball
(ii) Red ball
(iii) Black ball
(iv) Not red ball
Total number of balls 
(i) Total number white balls is 4
We know that PROBABILITY = 
Hence probability of getting white ball = 
(ii) Total number red balls are 3
We know that PROBABILITY =
Hence probability of getting red ball is
(iii) Total number of black balls is 5
We know that PROBABILITY =
Hence probability of getting black ball 
(iv) Total number of non red balls are 4 white balls and 5 black balls i.e. 
We know that PROBABILITY =
Hence probability of getting non red ball 