probability question, please help with explanation

Question

1.two green tiles, one red tile, and a blue tile

are put into a paper bag.

a) What is the probability that a green tile is drawn, followed by a blue tile, assuming the first tile is replaced before the second tile is drawn?

b) How does the answer to part a) change if the first tile drawn is not replaced?

c) Explain why these answers are different.

I really don't understand this question, I'm getting confused with the bolded part.

Answer 1

You have 4 tiles with a 2/4, aka 1/2 probability of selecting a green tile. If you put it back, you now have a 1/4 probability of selecting a blue tile.

(1/2)(1/4) = 1/8

If the first tile drawn is not replaced, you now have a 1/3 probability of drawing a blue tile.

(1/2)(1/3) = 1/6

The answers are different because replacement gives you a lower probability on the next draw.