…Then a second marble is drawn.
1. What is the probability of selecting a purple marble and then a white marble?
2. What is the probability of selecting two white marbles?
3. Is there a greater chance of selecting two white marbles in a row or two purple marbles in a row?
Don’t just tell me how to do it, give me some numbers please
2 Answers

All of these questions depend on the answer of what color marble was drawn first if it’s not replaced…that changes variables in determining the probability of the second event

1. The probability of selecting a purple marble is (# of purple marbles) / (total # of marbles).
The probability of selecting a white marble is (# of white marbles) / (total # of marbles).
After you draw the purple marble on the first draw, since you don’t replace it, the total # of marbles has changed.
Probability of both of these things happening = product of the probabilities.
2. Probability of drawing a white marble on the first draw = (# of white marbles) / (total # of marbles).
Probability of drawing a white marble on the second draw = (# of white marbles) / (total # of marbles).
Probability of both of these things happening = product of the probabilities.
After you draw a white marble on the first draw, both the # of white marbles and the total # of marbles for the second draw have changed. So those two probabilities are not the same.
3. Evaluate the probability of two purple marbles the way I did two white marbles.
Compare the two numbers.