There is a bag of 50 marbles.

Andre takes out a marble, records its color, and puts it back in. In 4 trials, he gets a green marble 1 time.
Jada takes out a marble, records its color, and puts it back in. In 12 trials, she gets a green marble 5 times.
Noah takes out a marble, records its color, and puts it back in. In 9 trials, he gets a green marble 3 times.
1. Which is the best estimate of the probability of getting a green marble from this bag?

If you want to find the probability of picking out a certain colored marble after you have already picked one out, then the probability changes, because now the total number of marbles you have is 32 instead of 33, and the probability of  the color you could pick out can change depending on what marble you picked out first.

For example, if you want to know the probability of picking out an orange marble the second time, and you didn't pick out a orange marble the first time, then you still have 10 orange marbles, but now you have 32 total marbles, so the probability will be 10 out of 32 instead of 10 out of 33. But if you picked out 1 orange marble already, and you didn't put it back in, then you will have a probability of picking out 9 out of 32 because there are 9 orange marbles left.

In short: If you pick a marble out the first time and then put it back in the pile before your friend picks one out, then the probability of picking a marble of a certain color will be the same the second time as the first time because there will still be the same number of marbles with the same number of the same colored marbles as the first time, but if you don't put the marble back in, then the probabilities will change.

Step-by-step explanation:

c. 4 and 1/2 pounds is the answer! : )