zero
It is 1/7 if a ball is selected at random.
3 out of 13 or 3/13
2
If the balls are selected at random, then the probability is 12/95.
3/5 probability of a white ball being drawn.
It is 1/7 if a ball is selected at random.
3/12*3/11 = 9/132, or 6.818%.
3 out of 13 or 3/13
2
If the balls are selected at random, then the probability is 12/95.
There are 18 Green balls and 12 Blue balls. You have to pick 2 blue balls, so the green balls don't matter. You can pick 1 blue ball on 12 ways. The second ball you can pick on 11 ways (because there are 11 balls left). 12 * 11 = 132. So you can pick it on 132 ways. ;)
2 in 7.
ans : 3720
3/5 probability of a white ball being drawn.
1/4
3c2+2c2+3c1 2c1 --------------- 7c2. I have done it this way. 3C2 means that the both balls would be green 2C2 both would be red and 3C1 and 2C1 because both the balls can be red and green.
There are 7 balls in total.4 are red and 1 is the blue "5" ball. Thus there are five balls out of the seven which meet the criteria and therefore the odds must be 5/7.The probabilities are mutually exclusive (i.e. you can not both draw a red ball and the "5" ball at the same time as the "5" is blue) so you just add the probabilities of each together.Probability of drawing a red ball = 4/7 (4 of the 7 balls are red)Probability of drawing the "5" ball = 1/7 (1 of the 7 balls is the "5" ball)Overall probability = 4/7 + 1/7 = 5/7