ezhilkumarank wrote:
rxs0005 wrote:
A bag has 100 marbles numbered consecutively 0 - 99 inclusive. Another bag has 60 marbles numbered consecutively 90 - 149 inclusive. If a marble is randomly chosen from each bag, what is the probability that two marbles have the same number
1/10
1/60
1/100
1/600
1/6000
My approach:
Pickup the matching 10 numbered marbles from the first bag -- Probability - 10/100 -- 1/10
Now we have one of the marble numbered from 90 - 99. From the other bag we need to pick just the one marble which will have a number from 90 - 99 to ensure we have a matching marble set. Its probability is 1/60.
Hence combined probability is (1/10) * (1/60) -- 1/600. Answer D.
There is a similar question in this forum , check this out --
http://gmatclub.com/forum/junior-58914.htmlmy approach.....
probability of picking a marble from 0 -99 in the first set = 1/100 { since 0-99 is hundred marbles}
similarly, probability of picking a marble from 90-149 in the second set = 1/60
therefore, probability that they are same = (1/100) * (1/60) = 1/6000
it can happen for 10 marbles ( 90 to 99 inclusive ) .
Thus, total probability = 10 *1/6000 =
1/600 ANS