Having issue with this question can anyone help?

GRE Quant Problem Solving
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doubt
doubt1673Ă—926 168 KB

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Is the answer C ?

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yes it is but how did you do it

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The answer for each of the quantity is 2/5 … just simulate the possibilities and find the probability …like for Quantity A in order to get Red in 3rd draw there are just BBR,RBR,BRR so all u need to do is find probability for each of the three events and add to get 2/5 …similarly for Quantity B u get 4 possibilities and the sum of those gives 2/5

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I think this question is testing your knowledge about “Independent v/s dependent event” and the clue is “without replacement” thus, making the events dependent on each other. Look at Greg’s Concept classes or search the google for dependent and Independent events and you’ll get it!

1 Like
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The probability of any event is the
Desired Outcome / Total Number of Outcomes.

For this problem, let’s have the table of outcomes.
R => Red Marble
B => Blue Marble

Outcome Table:

  1. BBBRR => B
  2. BBRBR => A
  3. BRBBR
  4. RBBBR
  5. RBBRB => B
  6. RBRBB => A
  7. RRBBB
  8. BRRBB => A
  9. BBRRB => A, B
  10. BRBRB => B

P(A): 4/10 => 2/5
P(B): 4/10 => 2/5

Therefore, C.