Compare and contrast dependent and independent events

Suppose you had a bag of 8 marbles, 3 red and 5 blue. What is the probability of choosing a red marble on the 3rd draw?

If the first two marbles are not replaced after being drawn, then the 3rd draw is an example of a dependent event, because, obviously, there won't be 8 marbles in the bag when we get to the 3rd draw, there will be 6.

Dependent or not, you'll still examine the sample space of possible outcomes in either case to correctly determine the probability-it's just that the possible outcomes may be fewer than you started with. So the dependent event changes the sample space but not how you ultimately calculate the probability.