In a box, there are 5 plastic balls and 10 wooden balls. Out of the 5 plastic balls, 3 are red and 2 are green. Similarly, the 10 wooden balls have 3 red and 7 green. What is the probability that a ball drawn from the box is either a plastic ball or red in color?

The event of interest is; “the drawn ball should be either a plastic ball or red in color”. There are 5 plastic balls. Number of red balls is 6; 3 plastic and 3 wooden. Plastic red balls are already counted in 5 plastic balls. But the 3 wooden red balls should be added to get the number of balls that are either red or of plastic. Thus number of such balls is 5+3 = 8. Since, there are total 15 balls; required probability is 8/15.