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 9/16. How many marbles are in the bag? Choose the correct choice from the following answers
A) 48
B) 24
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 48 occuring is m and the probability of event B occuring is n then the probability of both 48 and B 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 9/16   --&gt;(x-12)^2= 16/25   x^2   48   square rooting u have x-12/x = 3/4 or 4x-48 =3x or x = 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 9/16. How many marbles are in the bag?