Hi All,
Sequence questions are always based on a pattern of some kind, but there might be more to the pattern than you might initially realize. It often helps to "map out" the first few terms in a sequence question, so you can "see" the numbers and spot any hidden patterns involved.
Here, we're given the 'equation' for the sequence: bN = (2N-1)(2N+3) where N is the Nth term in the sequence....
1st term = (2-1)(2+3) = (1)(5) = 5
2nd term = (4-1)(4+3) = (3)(7) = 21
3rd term = (6-1)(6+3) = (5)(9) = 45
4th term = (8-1)(8+3) = (7)(11) = 77
Etc.
From this, we can deduce a number of details:
1) EVERY term will be an ODD INTEGER
2) The sequence of "products" will work through EVERY positive odd integer (notice the 1, the 3, the 5, the 7, etc).
This helps us to prove that Roman Numerals I and III COULD be true and that II is false.
Final Answer:
GMAT assassins aren't born, they're made,
Rich
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