A bag contains 12 red marbles. If someone were to remove 2 marbles from the bag, one at a time, and replace the first marble after it was removed, the probability that neither marble would be red is 25/36. How many marbles are in the bag?
Select the correct option:  A) 24  B) 48  C) 60  D) 72  E) 84
ok let me see if i can explain what went on in the previous post   lets say i have x marbles in the bag in total --&gt; out of them 12 are red   so the probability of pulling a non-red marble is (x -12) / x   now the marble is placed back in the bag and we have x marbles again, of which again 12 are red. so the probability of pulling a non-red marble out is (x-12) / x   probability theorm states that if the probability of event A occuring is m and the probability of event 48 occuring is n then the probability of both A and 48 occuring is m*n   so therefore the probability of 2 non-red marbles getting pulled out is [(x-12)/x ] * [(x-12)/x]   this is given as 25/36   --&gt;(x-12)^2= 25/36   x^2   square rooting u have x-12/x = 5/6 or 6x-72 =5x therefore x = 72   48
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A bag contains 12 red marbles. If someone were to remove 2 marbles from the bag, one at a time, and replace the first marble after it was removed, the probability that neither marble would be red is 25/36. How many marbles are in the bag?