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didieravoaka
- Master | Next Rank: 500 Posts
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- Joined: Tue Jan 13, 2015 11:44 am
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Hi didieravoaka,
You can approach the math in this question in a couple of different ways, so you have to think about what would be the easiest way for YOU to organize your work.
The questions tells us to roll a 6-sided dice 3 times. We're asked for the probability of rolling EXACTLY one '3' on those three rolls.
Here's a way to break the calculation down into 3 smaller calculations:
(first roll is 3)(second roll is NOT 3)(third roll is NOT 3) = (1/6)(5/6)(5/6) = 25/216
(first roll is NOT 3)(second roll is 3)(third roll is NOT 3) = (5/6)(1/6)(5/6) = 25/216
(first roll is NOT 3)(second roll is NOT 3)(third roll is 3) = (5/6)(5/6)(1/6) = 25/216
Total = 3(25/216) = 75/216 = 25/72
Final Answer: C
GMAT assassins aren't born, they're made,
Rich
