A bag contains 4 red balls, 3 green balls, and 5 yellow balls. What is the probability of drawing a red or a green ball?
We have a bag contains:
4 red balls
3 green balls
5 yellow balls
Then the total number of balls in the bag is 12 balls
The chances of drawing a red ball = number of red balls / total number of balls = 4/12 = 1/3
The chances of drawing a green ball = number of green balls/ total number of balls = 3/12 = 1/4
Now in probability the phrase OR translate as +
The the chances of drawing a red OR a green ball = chances of red + chances of green = 1/3 + 1/4 = 7/12
Probability is determined by the number of desired answers divided by the total number of answers. There are 12 possible balls you can draw so the denominator will be 12, there are 4 red balls and 3 green balls, so there are 7 balls that fit the requirement of being either red or green.
The probability of drawing either a red or a green ball is 7/12.