How many numbers of this sequence of 342 numbers are odd?
(1) The sequence starts with -1,3,-3,..........
(2) Except for the 1st two numbers, every number in the sequence is the product of the two immediately preceding numbers
OA is C
[spoiler]Should a pattern be considered after reading the first 3 terms -1,3,-3,..........
I mean to say, i considered a pattern, a bit early i.e between -1 & 3 there is a gap of 4
between 3 & -3 there is a gap of 6
then between -3 & 1 there is a gap of 4 and then again 6 and so on.
-1,3,-3,1,-5.......
thus this gives odd numbers.
I am considering patterns early. Should there be more terms to confirm this pattern ? or is it a wrong pattern as nothing is defined.[/spoiler]
Looking forward for an explanation.
Thanks & Regards
Vinni
How many numbers of this sequence of 342 numbers are odd?
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- Java_85
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Hi vinni.k,
(1) is not enough to answer the question.
(2) alone is also not sufficient. == > C or E
(1)(2) -1 3 -3 -9 27 ...
in this sequence all numbers will be odd, because all are multiples of 3 and only will have factor 3. ==> C
You don't need to calculate the gaps, just see how the series is going and weather an even factor have a way to get into the series or not, here it does not.
Cheers,
(1) is not enough to answer the question.
(2) alone is also not sufficient. == > C or E
(1)(2) -1 3 -3 -9 27 ...
in this sequence all numbers will be odd, because all are multiples of 3 and only will have factor 3. ==> C
You don't need to calculate the gaps, just see how the series is going and weather an even factor have a way to get into the series or not, here it does not.
Cheers,
- GMATGuruNY
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Statement 1: The sequence starts with -1,3,-3,....vinni.k wrote:How many numbers of this sequence of 342 numbers are odd?
(1) The sequence starts with -1,3,-3,..........
(2) Except for the 1st two numbers, every number in the sequence is the product of the two immediately preceding numbers
OA is C
Given only the first 3 terms, we cannot determine how each value in the sequence is calculated.
Thus, there is no way to know how many of the 342 terms will be odd.
INSUFFICIENT.
Statement 2: Except for the 1st two numbers, every number in the sequence is the product of the two immediately preceding numbers.
If the first two terms are 1 and 3, then all of the terms in the sequence will be ODD.
If the first two terms are 2 and 4, then all of the terms in the sequence will be EVEN.
INSUFFICIENT.
Statements combined:
Since we know the first two terms and the formula for computing every subsequent term, we can calculate every term in the sequence.
Thus, we can determine how many of the 342 terms will be odd.
SUFFICIENT.
The correct answer is C.
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Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
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