Natalya put 14 blue marbles, 14 red marbles, and no other marbles into

Question

Natalya put 14 blue marbles, 14 red marbles, and no other marbles into 3 empty cups. She put 2 blue marbles and 6 red marbles in Cup A, 6 blue marbles and 4 red marbles in Cup B, and 6 blue marbles and 4 red marbles in Cup C. After this, Dmitry will randomly pick three marbles, one from each cup.

Consistent with the given information, select for 3 blue the probability that Dmitry will pick 3 blue marbles, and select for 3 red the probability that Dmitry will pick 3 red marbles. Make only two selections, one in each column.

Apt0810 · Accepted Answer

Probability of 3 blue=

Picking blue from each cup
So probability of blue in Cup A = 2/8
probability of blue in Cup B= 6/10

probability of blue in Cup C= 6/10

So Probability of 3 blue= 2/8 * 6/10 *6/10 = 9/100= 0.090

Similarly 
Probability of 3 Red=

Picking blue from each cup
So probability of Red in Cup A = 6/8
probability of Red in Cup B= 4/10

probability of Red in Cup C= 4/10

So Probability of 3 Red= 6/8 * 4/10 *4/10 = 0.12

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nazii · Answer

I was thinking should we concsider different case of probability of getting for example all 3 blue marbles from cup B?
in that way the answer would be different !
 your response considered the case where one marble is picked from each cup, but I didn't such explicitly from question stem. How we should find it out? 
Dear  Sajjad1994 
what is official explanation. How we can resolve this ambiguity?

Sajjad1994 · Answer

1. Keep things simple and limited to the extent required by the question.
2. Do not overthink; it will spoil all of your conceptual work.
3. This question belongs to GMAT prep, so any ambiguity is near to impossible.

Why do we need to do that? when the question is specifically not asking to do that.

Dmitry will randomly pick three marbles, one from  each cup.

Rule 4: Do not assume things; read the question carefully and stick to it.

Thank you

sunshineeee · Answer

I got it solved with 2:51 time, how to solve it more quickly under 2 mins?

What I did,
1. I read it first
2. Then twice
3. then, take note the numbers
4. then, calculate it

Pls advise, thanku!!

Bunuel · Answer

This is a relatively easy and straightforward question, and ideally it should be solved in under 2 minutes. I am not sure which step took you longer than necessary, but most of the time on problems like this is lost either on rereading or on slow arithmetic. So one or both of these should be sped up: work on reading faster and calculating more quickly.

3 Blue	3 Red
		0.090
		0.120
		0.125
		0.150
		0.250
		0.500

Natalya put 14 blue marbles, 14 red marbles, and no other marbles into

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Natalya put 14 blue marbles, 14 red marbles, and no other marbles into

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