Find all School-related info fast with the new School-Specific MBA Forum

It is currently 20 Oct 2014, 18:28

Close

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

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If 5a=9b=15c, what is the value of a+b+c?

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
3 KUDOS received
Intern
Intern
avatar
Joined: 11 May 2013
Posts: 9
Followers: 0

Kudos [?]: 5 [3] , given: 0

If 5a=9b=15c, what is the value of a+b+c? [#permalink] New post 13 Jul 2013, 22:06
3
This post received
KUDOS
3
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  95% (hard)

Question Stats:

28% (02:43) correct 72% (01:51) wrong based on 485 sessions
If 5a=9b=15c, what is the value of a+b+c?

(1) 3c-a=5c-3b
(2) 6cb=10a

*Note - my answer is different from the official answer. I'm posting it here to confirm whether I'm correct or not.
[Reveal] Spoiler: OA
Expert Post
7 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23348
Followers: 3602

Kudos [?]: 28657 [7] , given: 2808

Re: If 5a=9b=15c, what is the value of a+b+c? [#permalink] New post 13 Jul 2013, 22:30
7
This post received
KUDOS
Expert's post
4
This post was
BOOKMARKED
If 5a=9b=15c, what is the value of a+b+c?

Given: 5a=9b=15c --> least common multiple of 5, 9, and 15 is 45 hence we can write: 5a=9b=15c=45x, for some number x --> a=9x, b=5x and c=3x.

(1) 3c-a=5c-3b --> 9x-9x=15x-15x --> 0=0 (this means that ANY appropriate values of a, b, and c satisfy the given statement). Not sufficient.

(2) 6cb=10a --> 6*3x*5x=10*9x --> 90x^2=90x --> x=0 or x=1. Not sufficient.

(1)+(2) x=0 or x=1, thus a=b=c=0 (for x=0) --> a+b+c=0 OR a=9, b=5, c=3 (for x=1) --> a+b+c=17. Not sufficient.

Answer: E.

Hope it's clear.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Expert Post
2 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23348
Followers: 3602

Kudos [?]: 28657 [2] , given: 2808

Re: If 5a=9b=15c, what is the value of a+b+c? [#permalink] New post 14 Jul 2013, 00:12
2
This post received
KUDOS
Expert's post
jabronyo wrote:
Thanks Bunnuel.

My answer was B.

Using the original question, I solved for a:

5a = 9b
a=9b/5

Then I substituted a into statement 2:

6cb = 10a
6cb = 10(9b/5)
6c = 90/5
30c = 90
c = 3

Once I have c , I calculated for a and b:

5a = 15(3)
a = 45/5
a = 9

9b = 15(3)
b = 5

a+b+c = 17


The problem with your solution is that you cannot reduce 6cb = 10(9b/5) by b. Doing so you exclude b=0 case:

6cb = 10(9b/5) --> cb=3b --> b(c-3)=0 --> b=0 or c=3.

Hope it's clear.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

1 KUDOS received
Intern
Intern
avatar
Joined: 11 May 2013
Posts: 9
Followers: 0

Kudos [?]: 5 [1] , given: 0

Re: If 5a=9b=15c, what is the value of a+b+c? [#permalink] New post 13 Jul 2013, 23:51
1
This post received
KUDOS
Thanks Bunnuel.

My answer was B.

Using the original question, I solved for a:

5a = 9b
a=9b/5

Then I substituted a into statement 2:

6cb = 10a
6cb = 10(9b/5)
6c = 90/5
30c = 90
c = 3

Once I have c , I calculated for a and b:

5a = 15(3)
a = 45/5
a = 9

9b = 15(3)
b = 5

a+b+c = 17
Expert Post
1 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23348
Followers: 3602

Kudos [?]: 28657 [1] , given: 2808

Re: If 5a = 9b = 15c, what is the value of a + b + c? [#permalink] New post 22 Aug 2013, 00:55
1
This post received
KUDOS
Expert's post
atewari wrote:
We have from question that a=3c, 3b=5c, 5a=9b

Statement 1

3c - a = 5c - 3b is the same as 3b-a=2c, substitute a with 3c, we get 5c=3b. Hence Statement 1 is Not Sufficient.

Statement 2

6cb = 10a is the same as 6cb = 30c,
Dividing both sides with 3c gives 2b = 10 and b = 5

With the value of b we can find that c = 3 and a = 9.

Hence statement 2 is Sufficient.

Thus the answer, B.


The correct answer is E, not B. Check here: if-5a-9b-15c-what-is-the-value-of-a-b-c-155926.html#p1246081 and here: if-5a-9b-15c-what-is-the-value-of-a-b-c-155926.html#p1246110

Hope it helps.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Senior Manager
Senior Manager
avatar
Joined: 10 Jul 2013
Posts: 343
Followers: 3

Kudos [?]: 120 [0], given: 102

If 5a = 9b = 15c, what is the value of a + b + c? [#permalink] New post 21 Aug 2013, 16:41
If 5a = 9b = 15c, what is the value of a + b + c?
(1) 3c – a = 5c – 3b
(2) 6cb = 10a
_________________

Asif vai.....

Intern
Intern
User avatar
Joined: 04 Jul 2013
Posts: 4
Followers: 0

Kudos [?]: 1 [0], given: 3

Re: If 5a = 9b = 15c, what is the value of a + b + c? [#permalink] New post 21 Aug 2013, 20:12
We have from question that a=3c, 3b=5c, 5a=9b

Statement 1

3c - a = 5c - 3b is the same as 3b-a=2c, substitute a with 3c, we get 5c=3b. Hence Statement 1 is Not Sufficient.

Statement 2

6cb = 10a is the same as 6cb = 30c,
Dividing both sides with 3c gives 2b = 10 and b = 5

With the value of b we can find that c = 3 and a = 9.

Hence statement 2 is Sufficient.

Thus the answer, B.
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23348
Followers: 3602

Kudos [?]: 28657 [0], given: 2808

Re: If 5a = 9b = 15c, what is the value of a + b + c? [#permalink] New post 22 Aug 2013, 00:54
Expert's post
Asifpirlo wrote:
If 5a = 9b = 15c, what is the value of a + b + c?
(1) 3c – a = 5c – 3b
(2) 6cb = 10a


Merging similar topics. Provided OA (B) is NOT correct. Check here: if-5a-9b-15c-what-is-the-value-of-a-b-c-155926.html#p1246081

Hope it helps.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Manager
Manager
User avatar
Joined: 23 Jan 2013
Posts: 147
Followers: 0

Kudos [?]: 12 [0], given: 22

Re: If 5a=9b=15c, what is the value of a+b+c? [#permalink] New post 22 Aug 2013, 09:38
If 5a=9b=15c, what is the value of a+b+c?

(1) 3c-a=5c-3b
(2) 6cb=10a

*Note - my answer is different from the official answer. I'm posting it here to confirm whether I'm correct or not.[/quote]

Statement 1: insufficient because having infinitely many solutions
Statement 2:
6cb=10a means that
6cb=18b and 6cb=30c, so
cb=3b and cb=5c
c=3b/b=3 and b=5c/c=5 providing that c and b are not equal to 0. So I think ambiguity with 0 is resolved and a=9 so sum is 17. Sufficient
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23348
Followers: 3602

Kudos [?]: 28657 [0], given: 2808

Re: If 5a=9b=15c, what is the value of a+b+c? [#permalink] New post 22 Aug 2013, 09:41
Expert's post
Temurkhon wrote:
If 5a=9b=15c, what is the value of a+b+c?

(1) 3c-a=5c-3b
(2) 6cb=10a

*Note - my answer is different from the official answer. I'm posting it here to confirm whether I'm correct or not.

Statement 1: insufficient because having infinitely many solutions
Statement 2:
6cb=10a means that
6cb=18b and 6cb=30c, so
cb=3b and cb=5c
c=3b/b=3 and b=5c/c=5 providing that c and b are not equal to 0. So I think ambiguity with 0 is resolved and a=9 so sum is 17. Sufficient


The correct answer is E, not B. Check:
if-5a-9b-15c-what-is-the-value-of-a-b-c-155926.html#p1246081
if-5a-9b-15c-what-is-the-value-of-a-b-c-155926.html#p1246110
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Manager
Manager
avatar
Status: Persevering
Joined: 15 May 2013
Posts: 224
Location: India
Concentration: Technology, Leadership
GMAT Date: 08-02-2013
GPA: 3.7
WE: Consulting (Consulting)
Followers: 1

Kudos [?]: 53 [0], given: 34

GMAT ToolKit User
Re: If 5a=9b=15c, what is the value of a+b+c? [#permalink] New post 24 Aug 2013, 04:57
OA is E; As correctly pointed out by bunuel

You cannot simply reduce an expression ab=bc does not imply that a=c, as it is perfectly possible for b to be zero and var a might not be equal to var c.
_________________

--It's one thing to get defeated, but another to accept it.

Senior Manager
Senior Manager
avatar
Joined: 07 Sep 2010
Posts: 340
Followers: 3

Kudos [?]: 156 [0], given: 136

Re: If 5a=9b=15c, what is the value of a+b+c? [#permalink] New post 24 Aug 2013, 06:01
Bunuel wrote:

(1)+(2) x=0 or x=1, thus a=b=c=0 (for x=0) --> a+b+c=0 OR a=9, b=5, c=3 (for x=1) --> a+b+c=17. Not sufficient.

Answer: E.

Hope it's clear.


Hi Bunuel,

When combining St 1 and St2, isn't the only acceptable solution is when x=0, since x=0 is common to both statements.
How x=1 validates both the statements?
Pls clarify?
_________________

+1 Kudos me, Help me unlocking GMAT Club Tests

Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23348
Followers: 3602

Kudos [?]: 28657 [0], given: 2808

Re: If 5a=9b=15c, what is the value of a+b+c? [#permalink] New post 25 Aug 2013, 06:29
Expert's post
imhimanshu wrote:
Bunuel wrote:

(1)+(2) x=0 or x=1, thus a=b=c=0 (for x=0) --> a+b+c=0 OR a=9, b=5, c=3 (for x=1) --> a+b+c=17. Not sufficient.

Answer: E.

Hope it's clear.


Hi Bunuel,

When combining St 1 and St2, isn't the only acceptable solution is when x=0, since x=0 is common to both statements.
How x=1 validates both the statements?
Pls clarify?


The part you are quoting gives two examples:
a=b=c=0
a=9, b=5, c=3
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Manager
Manager
avatar
Joined: 14 Aug 2005
Posts: 87
Followers: 0

Kudos [?]: 6 [0], given: 2

GMAT ToolKit User CAT Tests
Re: If 5a=9b=15c, what is the value of a+b+c? [#permalink] New post 25 Aug 2013, 19:11
Bunuel wrote:
jabronyo wrote:
Thanks Bunnuel.

My answer was B.

Using the original question, I solved for a:

5a = 9b
a=9b/5

Then I substituted a into statement 2:

6cb = 10a
6cb = 10(9b/5)
6c = 90/5
30c = 90
c = 3

Once I have c , I calculated for a and b:

5a = 15(3)
a = 45/5
a = 9

9b = 15(3)
b = 5

a+b+c = 17


The problem with your solution is that you cannot reduce 6cb = 10(9b/5) by b. Doing so you exclude b=0 case:

6cb = 10(9b/5) --> cb=3b --> b(c-3)=0 --> b=0 or c=3.

Hope it's clear.


I made the same mistake! Thanks Brunel for pointing it out
_________________

One Last Shot

CEO
CEO
User avatar
Joined: 09 Sep 2013
Posts: 2791
Followers: 206

Kudos [?]: 42 [0], given: 0

Premium Member
Re: If 5a=9b=15c, what is the value of a+b+c? [#permalink] New post 30 Aug 2014, 07:44
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Manager
Manager
User avatar
Joined: 22 Jan 2014
Posts: 63
Followers: 0

Kudos [?]: 10 [0], given: 55

Re: If 5a=9b=15c, what is the value of a+b+c? [#permalink] New post 31 Aug 2014, 02:27
jabronyo wrote:
If 5a=9b=15c, what is the value of a+b+c?

(1) 3c-a=5c-3b
(2) 6cb=10a

*Note - my answer is different from the official answer. I'm posting it here to confirm whether I'm correct or not.


My take is E.

5a=9b=15c
LCM(5,9,15) = 45.
=> a = 9x, b = 5y, and c = 3z

1) 3c-a=5c-3b
=> 6z = 15y-9x
or 2z = 5y - 3x

y and x must be odd for LHS to be even. so multiple solutions exist.

2) 6cb = 10a
6*5y*3z = 10*9x
x = yz

x=y=z=0
or x=y=z=1
not sufficient.

1)+2)
x=y=z=0
or x=y=z=1
not sufficient.

Hence, E.
_________________

Illegitimi non carborundum.

Intern
Intern
avatar
Joined: 03 Jul 2014
Posts: 19
Location: United States
Concentration: Finance, Strategy
Schools: Insead '14, NUS '16
GMAT Date: 10-17-2014
GPA: 4
WE: Analyst (Insurance)
Followers: 0

Kudos [?]: 6 [0], given: 21

Re: If 5a=9b=15c, what is the value of a+b+c? [#permalink] New post 04 Sep 2014, 17:45
Hi all,

My answer is E.

Given: 5a = 9b = 15c
to find: a+b+c


Let us suppose 5a = 9b = 15c = K (some constant)
Therefore, a= K/5, b = K/9, and c = K/15

a+b+c = K/5 + K/9 + K/15 = 17K/45
Now we have to find K

statement 1 : 3c-a = 5c-3b
3*(K/15)-(K/5) = 5*(K/15)-3*(K/9)
This reduces to 0=0
hence, statement 1 alone is not sufficient

statement 2: 6cb = 10a
I'll write this as 6cb-10a = 0

6*(K/15)*(K/9)-10(K/5) = 0
=> 2*(K^2)/45 - 2*K =
=> 2K(K/45 - 1) =
either K = 0 or K = 45
so a+b+c = 17K/45 = 0 or 17
hence, statement 2 alone is not sufficient


statement 1 and statement 2 together will not suffice because statement 1 reduces to 0.

Hence, the correct answer is E.

--------------------------------------------------------------------------------
Kudos if this helps :-D
Re: If 5a=9b=15c, what is the value of a+b+c?   [#permalink] 04 Sep 2014, 17:45
    Similar topics Author Replies Last post
Similar
Topics:
If 5a = 9b = 15c, what is the value of a + b + c? Asifpirlo 0 21 Aug 2013, 20:12
6 What is the value of product abc? VeritasPrepBrian 13 16 Nov 2010, 17:12
If a,b,c are inetegers .What would be the value of a ? dreamgmat1 4 09 Jun 2007, 19:16
If abc is not equal to 0, what is the value of Himalayan 5 14 May 2007, 19:53
If 5a=9b=15c, what is the value of a+b+c? 1. 3c-a=5c-3b 2. GMATT73 15 08 Oct 2006, 07:09
Display posts from previous: Sort by

If 5a=9b=15c, what is the value of a+b+c?

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.