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Number of variation!

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Number of variation!

by Ahmed MS » Sat Oct 29, 2011 9:56 pm
Q: For a finite sequence of nonzero numbers, the numbers of variation in sign is defined as the number of pairs of consecutive terms of the sequence for which the product of the two consecutive terms is negative. What is the number of variations in sign for the sequence 1, -3, 2, 5, -4, -6?

1.One
2. Two
3. Three
4. Four
5. Five

OA is Three.

I have failed to understand the question. Please help me!


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by vaibhavgupta » Sat Oct 29, 2011 11:13 pm
Ahmed MS wrote:Q: For a finite sequence of nonzero numbers, the numbers of variation in sign is defined as the number of pairs of consecutive terms of the sequence for which the product of the two consecutive terms is negative. What is the number of variations in sign for the sequence 1, -3, 2, 5, -4, -6?

1.One
2. Two
3. Three
4. Four
5. Five

OA is Three.

I have failed to understand the question. Please help me!


Cheers!
Variation will be when the preceding number*present number is negative
and present number* succeeding number is negative

1,-3 -3,2 5,-4 's prduct will be negative

Hence variation 3.

Pls put OA in spoiler next time ! :)
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by rijul007 » Sat Oct 29, 2011 11:16 pm
Sequence => 1,-3,2,5,-4,-6

total no of pairs of consecutive terms
(1,-3)
(-3,2)
(2,5)
(5,-4)
(-4,-6)

the product of the two consecutive terms is negative=> this implies that the nos in each pair are opposite in sign, which is true for the following pairs
=> (1,-3),(-3,2) and (5,-4)

Hence, the correct option is 3.
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by Ahmed MS » Sat Oct 29, 2011 11:48 pm
vaibhavgupta wrote:
Ahmed MS wrote:Q: For a finite sequence of nonzero numbers, the numbers of variation in sign is defined as the number of pairs of consecutive terms of the sequence for which the product of the two consecutive terms is negative. What is the number of variations in sign for the sequence 1, -3, 2, 5, -4, -6?

1.One
2. Two
3. Three
4. Four
5. Five

OA is Three.

I have failed to understand the question. Please help me!


Cheers!
Variation will be when the preceding number*present number is negative
and present number* succeeding number is negative

1,-3 -3,2 5,-4 's prduct will be negative

Hence variation 3.

Pls put OA in spoiler next time ! :)

Huh....huh. :-) I will. Thanks for your clarification.
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by GmatKiss » Sun Oct 30, 2011 2:21 am
too easy.. 3
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