In: Statistics and Probability
Total number of balls=19
Number of red balls =3
Number of green balls=10
Number of blue balls=6
Let R be the event of picking Red ball, G be the event of picking Green ball and B be the event of picking Blue ball
Then
1. We want to find the probability that the ball is blue or green.
probability of picking blue or green = since the events B and G are disjoint
Now,
We may also see that total number of balls that are green or blue is 16. and hence probability of getting a green or blue ball is 16/19
(2) We want to find the probability that the ball is blue given that it is not red
That is
We may also see that if it is given that the ball is not red, there are total 16 balls remaining and out of these 16, 6 are blue . So probability that the ball is blue given that it is not red is 6/16=3/8.