Two balls are drawn in succession out of a box containing 5 red and 5 white balls. find the probability that at least 1 ball was red, given that the first ball was
a- replaced before the second draw.
b- not replaced before the second draw.

Ok so, 

One bag of 5 red and 5 white balls.

Two were taken out of the bag, they didn't mention what color they were.

If there were 10 balls total, and 5 of them are red, how many red balls could have possibly been pulled out of the bag?

So, the probability that one ball was red is 1/5 because there are only 5 red balls in the bag. 

A) If it was replaced before the second draw, the probability would still be 1/5 because they put the red ball back.

B) If it was not replaced before the second draw, the probability would be 1/4 being that there are now only 4 red balls left in the bag.