3 out of 13 or 3/13
zero
0.4
17 out of 21
That depends. Picking a red ball is 4/9 Picking a green ball is 3/9 = 1/3 Picking a yellow ball is 2/9. Picking a ball is 9/9 or 1 because you'll always take one.
2 in 7.
The probability is zero, because there are no red balls in the bag.
12
Drawing one red ball out of a bag that contains 3 red balls and 4 green balls is 3 in 7. If we are to randomly select one ball out of the bag and replace it (I assume with the same ball) then there are still 3 red balls and 4 green balls. The odds are still 3 in 7. It doesn't matter how many times you draw. Every time you draw a ball you have a 3 in 7 chance of pulling out a red ball.
3 out of 13 or 3/13
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.
Thrice means three times as many. If you have two green balls, it would mean you have six red balls.
zero
If you draw enough balls, without replacement, the probability is 1.The answer depends onhow many balls are drawn, andwhether or not they are replaced.Unfortunately, your question gives no information on these matters.
Santa's bag is green
Probability of first green: 5/7Probability of second green: 5/7Probability of a red: 2/7Probability of all 3 consecutive successes: (5/7) x (5/7) x (2/7) = 50/343 = 14.58% (rounded)
Fractional is 3/6 or 1/2