For a finite sequence of non zero numbers, the number of

[BTGmoderatorDC]

For a finite sequence of non zero numbers, the number of variations 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 ?

A. 1
B. 2
C. 3
D. 4
E. 5

OA C

Source: GMAT Prep

[Jay@ManhattanReview]

For a finite sequence of non zero numbers, the number of variations 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 ?

A. 1
B. 2
C. 3
D. 4
E. 5

OA C

Source: GMAT Prep

Taking all the possible pairs of consecutive terms out of the sequence 1, -3, 2, 5, -4, -6:

1. {1, - 3}: Product = -3, negative
2. {- 3, 2}: Product = -6, negative
3. {2, 5}: Product = 10, positive
4. {5, - 4}: Product = -20, negative
5. {-4, - 6}: Product = 24, positive

We see that three products are negative, thus, the number of variations in sign = 3.

The correct answer: C

Hope this helps!

-Jay
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[Scott@TargetTestPrep]

For a finite sequence of non zero numbers, the number of variations 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 ?

A. 1
B. 2
C. 3
D. 4
E. 5

We are given the following sequence of numbers: 1, -3, 2, 5, -4, -6.

Every time a pair of consecutive terms produces a negative product, we have a "variation in sign." We must determine the number of variations in sign in the sequence.

1 x (-3) = -3, so this is a variation in sign

(-3) x 2 = -6, so this is a variation in sign

(2) x (5) = 10, so this is NOT a variation in sign

5 x (-4) = -20, so this is a variation in sign

(-4) x (-6) = 24, so this is NOT a variation in sign

Thus, there is a total of 3 variations in sign.

Answer: C

[Brent@GMATPrepNow]

For a finite sequence of non zero numbers, the number of variations 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 ?

A. 1
B. 2
C. 3
D. 4
E. 5

OA C

Source: GMAT Prep

We're asked to look at every pair of consecutive numbers. If the product of that pair is negative, this counts as one variation.

Let's examine the pairs of consecutive numbers:

1 and -3: product is negative
-3 and 2: product is negative
2 and 5: product is positive
5 and -4: product is negative
-4 and -6: product is positive

Since 3 pairs of consecutive numbers have negative products, the correct answer is C

Cheers,
Brent