Number of variation!

Expert replies

Ahmed MS: Senior | Next Rank: 100 Posts; Posts: 74; Joined: Wed Apr 06, 2011 8:35 pmFollowed by: 1 member

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!

Cheers!

Like this post

Source: Beat The GMAT — Problem Solving | Sat Oct 29, 2011 9:56 pm

vaibhavgupta: Master | Next Rank: 500 Posts; Posts: 416; Joined: Tue Aug 30, 2011 2:18 pmFollowed by: 9 members; Location: Delhi, India; Thanked: 13 times

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 !

Like this post

rijul007: Legendary Member; Posts: 588; Joined: Sun Oct 16, 2011 9:42 amFollowed by: 9 members; Location: New Delhi, India; Thanked: 130 times; GMAT Score:720

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.

Like this post

Ahmed MS: Senior | Next Rank: 100 Posts; Posts: 74; Joined: Wed Apr 06, 2011 8:35 pmFollowed by: 1 member

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.

Like this post

GmatKiss: Legendary Member; Posts: 2789; Joined: Tue Jul 26, 2011 12:19 amFollowed by: 43 members; Location: Chennai, India; Thanked: 206 times; GMAT Score:640

by GmatKiss » Sun Oct 30, 2011 2:21 am

too easy.. 3

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

559 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review