If there are 3 red marbles, 5 green marbles, and 2 blue marbles, we can find the probability of finding one of them easily. If we add these numbers up, we get 10, so the red marbles plus the green marbles = 8 and then there are 2 blue ones. This means that there is an 80% chance of pulling a red or a green marble. Number one is correct. Now, number two. The probability of drawing a red marble followed by a green marble depends on each individual probability. For a red marble, that is 3/10 = 30% chance, and a green marble is 5/10 = 50% chance. Since we are drawing out of 20 marbles (Two sets of ten), we can conclude that the chances for red are 6/20; green's chances are 10/20, and blue's chances are 4/20. Assuming that we draw a red marble first, there is a 6/20 chance of that. There is a 10/20 chance of drawing a green, so we can conclude that the probability of drawing a red marble followed by a green marble is 4/20 (10/20 - 6/20). Number three... The probability of drawing a blue marble is 20%, so the probability of not drawing a blue marble is 80%. Number three is not true. Number four: The probability of drawing a green marble is 50% and the probabilities of red and blue combined are equal to 50%, so number four is correct. Hope this helps.