Events & Promotions
|
|
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Apr 2512:30 AM EDT
-01:30 AM EDT
At one point, she believed GMAT wasn’t for her. After scoring 595, self-doubt crept in and she questioned her potential. But instead of quitting, she made the right strategic changes. The result? A remarkable comeback to 695. Check out how Saakshi did it.
Apr 2610:00 AM EDT
-11:00 AM EDT
The Target Test Prep course represents a quantum leap forward in GMAT preparation, a radical reinterpretation of the way that students should study. Try before you buy with a 5-day, full-access trial of the course for FREE!
Apr 2711:00 AM EDT
-12:00 PM EDT
Prefer video-based learning? The Target Test Prep OnDemand course is a one-of-a-kind video masterclass featuring 400 hours of lecture-style teaching by Scott Woodbury-Stewart, founder of Target Test Prep and one of the most accomplished GMAT instructors
Apr 2808:00 AM PDT
-11:00 AM PDT
Whether you are just beginning your MBA journey or fine-tuning your path to a 700+ score, GMAT Day is designed to give you a competitive edge.
22 Mar 2011, 11:05
Kudos
Bookmarks
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
95%
(hard)
Question Stats:
32% (01:42) correct
68%
(01:59)
wrong
based on 414
sessions
History
Date
Time
Result
Not Attempted Yet
If abc ≠ 0, what is the value of \(\frac{a^3 + b^3 + c^3}{abc}\) ?
(1) \(|a|=1, |b|=2, |c|=3\)
(2) \(a + b + c = 0\)
(1) \(|a|=1, |b|=2, |c|=3\)
(2) \(a + b + c = 0\)
22 Mar 2011, 11:28
Kudos
Bookmarks
Statement 1:
|a|=1, |b|=2, |c|=3
So a, b, c can be positive or negative. Thus, the value of the expression cannot be uniquely determined.
NS
Statement 2:
a + b + c = 0
(a + b + c)^3 = a^3 + b^3 + c^3 + (3ab + 3bc + 3ca) (a + b + c) – 3abc
Substitute for a + b + c = 0 in the above equation:
0 = a^3 + b^3 + c^3 - 3abc
=> 3abc = a^3 + b^3 + c^3
=> (a^3 + b^3 + c^3)/abc = 3
Sufficient
|a|=1, |b|=2, |c|=3
So a, b, c can be positive or negative. Thus, the value of the expression cannot be uniquely determined.
NS
Statement 2:
a + b + c = 0
(a + b + c)^3 = a^3 + b^3 + c^3 + (3ab + 3bc + 3ca) (a + b + c) – 3abc
Substitute for a + b + c = 0 in the above equation:
0 = a^3 + b^3 + c^3 - 3abc
=> 3abc = a^3 + b^3 + c^3
=> (a^3 + b^3 + c^3)/abc = 3
Sufficient
General Discussion
22 Mar 2011, 11:29
Kudos
Bookmarks
since abc ≠ 0 , we know that either all numbers can be +ve or any two can be -ve
Option A does not help to solve the problem since we can not make out that which numbers can be -ve and value changes with every trial and error method. Therefore, A can not be the answer.
Option B tells us that A+B+C=0, therefore we can use the formula that
\(a^3 + b^3 + C^3 - 3abc = (a+b+c) (a^2 + b^2 + c^2 - ab - bc - ac)\)
and since we know that a+b+c = 0 then \(a^3 + b^3 + c^3 = 3abc\)
And thus putting "3abc" at the place of \(a^3 + b^3 + c^3\), will give us the answer.
Therefore answer is "B"
Only thing that since I know the formula thats why I could solve this problem within seconds ..... how to solve if we do not know the formula .... please someone explain.
Option A does not help to solve the problem since we can not make out that which numbers can be -ve and value changes with every trial and error method. Therefore, A can not be the answer.
Option B tells us that A+B+C=0, therefore we can use the formula that
\(a^3 + b^3 + C^3 - 3abc = (a+b+c) (a^2 + b^2 + c^2 - ab - bc - ac)\)
and since we know that a+b+c = 0 then \(a^3 + b^3 + c^3 = 3abc\)
And thus putting "3abc" at the place of \(a^3 + b^3 + c^3\), will give us the answer.
Therefore answer is "B"
Only thing that since I know the formula thats why I could solve this problem within seconds ..... how to solve if we do not know the formula .... please someone explain.
