n is a positive odd integer. What is the value of n?

[Max@Math Revolution]

[GMAT math practice question]

n is a positive odd integer. What is the value of n?

1) n, n + 2, n + 4 are prime numbers.
2) n - 1 is an even prime number.

[Max@Math Revolution]

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Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

The first step of the VA (Variable Approach) method is to modify the original condition and the question. We then recheck the question.

Condition 1):
The triple 3, 5 and 7 is the unique triple made up of three consecutive odd prime numbers number. So, n = 3.
Thus, condition 1) is sufficient.

Condition 2):
Since n - 1 = 2 is the unique even prime number, we must have n = 3. Thus, condition 2) is sufficient.

Therefore, D is the answer.
Answer: D