What is the value of v3 - k3 (read as v cube - k cube)?
(1) v k > 0
(2) v - k = 6
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
DS-Cube
This topic has expert replies
-
sanyalpritish
- Master | Next Rank: 500 Posts
- Posts: 106
- Joined: Tue Mar 23, 2010 8:04 pm
- Thanked: 2 times
-
gmatmachoman
- Legendary Member
- Posts: 2326
- Joined: Mon Jul 28, 2008 3:54 am
- Thanked: 173 times
- Followed by:2 members
- GMAT Score:710
St 1 just says that V &K should be +ve. Insufficient.sanyalpritish wrote:What is the value of v3 - k3 (read as v cube - k cube)?
(1) v k > 0
(2) v - k = 6
St 2: V & K can take any value to get 6: (7,1) or (8,2) etc;
Insufficient
So E
-
ajith
- Legendary Member
- Posts: 1275
- Joined: Thu Sep 21, 2006 11:13 pm
- Location: Arabian Sea
- Thanked: 125 times
- Followed by:2 members
1. Clearly Insufficientsanyalpritish wrote:What is the value of v3 - k3 (read as v cube - k cube)?
(1) v k > 0
(2) v - k = 6
2. Insufficient to know the value of v^3-k^3
combined also Insufficient
[spoiler]
So E[/spoiler]
Please not that had the value for vk is given as a number rather than as an inequality, it would have been possible to calculate v^3-k^3 with the help of both the statements
Always borrow money from a pessimist, he doesn't expect to be paid back.
-
sanyalpritish
- Master | Next Rank: 500 Posts
- Posts: 106
- Joined: Tue Mar 23, 2010 8:04 pm
- Thanked: 2 times
GMAT/MBA Expert
-
[email protected]
- Elite Legendary Member
- Posts: 10392
- Joined: Sun Jun 23, 2013 6:38 pm
- Location: Palo Alto, CA
- Thanked: 2867 times
- Followed by:511 members
- GMAT Score:800
Hi Nina1987,
Having a strong 'instinct' can be beneficial on Test Day, but you have to focus more on proving that you're correct. The work involved in many DS questions is relatively simple algebra/arithmetic, so rather than trying to 'talk your way past' a prompt, do the necessary work to PROVE what the correct answer is. In this prompt, you can TEST VALUES and quickly prove the correct answer in under a minute.
GMAT assassins aren't born, they're made,
Rich
Having a strong 'instinct' can be beneficial on Test Day, but you have to focus more on proving that you're correct. The work involved in many DS questions is relatively simple algebra/arithmetic, so rather than trying to 'talk your way past' a prompt, do the necessary work to PROVE what the correct answer is. In this prompt, you can TEST VALUES and quickly prove the correct answer in under a minute.
GMAT assassins aren't born, they're made,
Rich
GMAT/MBA Expert
-
Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
Target question: v³ - k³?sanyalpritish wrote:What is the value of v³ - k³ ?
(1) vk > 0
(2) v - k = 6
Statement 1: vk > 0
This statement doesn't FEEL sufficient, so I'll TEST some values.
There are several values of v and k that satisfy statement 1. Here are two:
Case a: v = 1 and k = 1, in which case v³ - k³ = 1³ - 1³ = 0
Case b: v = 2 and k = 1, in which case v³ - k³ = 2³ - 1³ = 7
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT
Aside: For more on this idea of plugging in values when a statement doesn't feel sufficient, you can read my article: https://www.gmatprepnow.com/articles/dat ... lug-values
Statement 2: v - k = 6
This statement doesn't FEEL sufficient either, so I'll TEST some values.
There are several values of v and k that satisfy statement 2. Here are two:
Case a: v = 7 and k = 1, in which case v³ - k³ = 7³ - 1³ = some big number
Case b: v = 8 and k = 2, in which case v³ - k³ = 8³ - 2³ = a DIFFERENT big number
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT
NOTE: I'm not going to waste time calculating 7³ - 1³ and 8³ - 2³. A see that they evaluate to be different values, which means I can't answer the target question. That's all I need to know.
Statements 1 and 2 combined
NOTICE that the numbers I tested for statement 2 ALSO satisfy statement 1. We have:
Case a: v = 7 and k = 1, in which case v³ - k³ = 7³ - 1³ = some big number
Case b: v = 8 and k = 2, in which case v³ - k³ = 8³ - 2³ = a DIFFERENT big number
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT
Answer = E
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
