Question 946484

there are 4 white balls out of 7 in the urn to start with.


the probability of drawing a white ball on the first draw is therefore 4/7.


your first draw is a white ball.


there are 3 white balls out of 6 left in the urn after the first draw.


the probability of drawing a white ball on the second draw is therefore 3/6.


your second draw is a white ball.


there are 2 white balls out of 5 left in the urn after the second draw.


the probability of drawing a white ball on the third draw is therefore 2/5.


given that you drew a white ball on the first 2 draws, the probability of drawing a white ball on the third draw is 2/5 because there are 2 white balls left out of a total of 5 balls left in the urn.


that's my understanding.