Bunuel wrote:
FRESH GMAT CLUB QUESTION:
A fair six-sided dice was rolled n times. What is the value of n?
(1) The number of different possible sequences of n-digit numbers when a dice is rolled n times is 7776.
(2) If the dice has been rolled 3 times fewer, the probability of getting a 6 on every roll would have been 1/36.
We need to see if we can create an equation with only variable, n.
We'll look for an answer that gives us this information, a Logical approach.
(1) Even if we don't know that 'the number of possible sequences...' is 6^n, then we should know that this has only one solution.
That is, there is only equation that can be created from this statement and it has only one variable - n.
Sufficient.
(2) There is only one way to get a 6 on every roll so a probability of 1/36 means the total number of options is 36.
That is, at 3 less rolls the total number of possible sequences is 36.
This is almost exactly the same as (1).
Sufficient.
(D) is our answer.
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67% (01:26) correct 
