You choose one of two identical looking bags at random. One bag has three black marbles and one white marble. The other has three white marbles and one black marble.

After choosing a bag you draw one marble out at random. You notice it is black. You then put it back and draw another marble out of the same bag at random.

What is the probability that the second marble drawn is black?

I don't understand probablity. Since the first ball picked is then replaced, does it have any relevance what colour it was? Are you not back at square one, with the question just coming down to what are the odds of drawing a black ball from one of the bags. Ill leave it to someone else to give the odds for this.

Posted by nellie on 2003-10-14 07:05:04