|
Author |
Message |
|
TAGS:
|
|
|
Manager
Joined: 01 Sep 2012
Posts: 93
Followers: 1
Kudos [?]:
4
[0], given: 18
|
In a certain economy, C represents the total amount of [#permalink]
 14 Dec 2012, 13:27
Question Stats:
50% (02:29) correct
50% (00:49) wrong based on 1 sessions
In a certain economy, C represents the total amount of consumption in millions of dollars, Y represents the total national income in millions of dollars, and the relationship between these two values is given by the equation C=90+9Y/11. If the total amount of consumption in the economy increases by 99 million dollars, what is the increase in the total national income, in millions of dollars? A.11 B.22 C.99 D.121 E.171 I tried several different approaches any tried to input numbers to see how it reacts but nothing worked... can someone care to explain?
_________________
If my answer helped, dont forget KUDOS! 
IMPOSSIBLE IS NOTHING
|
|
|
|
|
|
|
Director
Joined: 02 Jul 2012
Posts: 764
Location: India
Concentration: Strategy
GMAT 1: 740 Q49 V42
GPA: 3.8
WE: Engineering (Energy and Utilities)
Followers: 19
Kudos [?]:
259
[3] , given: 45
|
Re: In a certain economy, C represents the total amount of [#permalink]
14 Dec 2012, 21:00
3
This post received
KUDOS
roygush wrote: In a certain economy, C represents the total amount of consumption in millions of dollars, Y represents the total national income in millions of dollars, and the relationship between these two values is given by the equation C=90+9Y/11. If the total amount of consumption in the economy increases by 99 million dollars, what is the increase in the total national income, in millions of dollars?
A.11
B.22
C.99
D.121
E.171
I tried several different approaches any tried to input numbers to see how it reacts but nothing worked...
can someone care to explain? C_{old} = 90 + \frac{9Y_{old}}{11}Y_{old} = \frac{(C_{old} - 90)*11}{9}Y_{new} = \frac{(C_{old} + 99 - 90)*11}{9} = \frac{(C_{old} + 9)*11}{9}Increase = Y_{new} - Y_{old} = \frac{(C_{old} + 9)*11}{9} - \frac{(C_{old} - 90)*11}{9} = \frac{99*11}{9}= 121 Answer is D
_________________
Kudos Please... If my post helped.
Thanks To The Almighty - My GMAT Debrief
My Own CR Question 1|My Own CR Question 2|My Own DS Question 1|My Own DS Question 2|
My Own PS Question 1
|
|
|
|
|
|
Manager
Joined: 01 Sep 2012
Posts: 93
Followers: 1
Kudos [?]:
4
[0], given: 18
|
Re: In a certain economy, C represents the total amount of [#permalink]
15 Dec 2012, 03:07
MacFauz wrote: roygush wrote: In a certain economy, C represents the total amount of consumption in millions of dollars, Y represents the total national income in millions of dollars, and the relationship between these two values is given by the equation C=90+9Y/11. If the total amount of consumption in the economy increases by 99 million dollars, what is the increase in the total national income, in millions of dollars?
A.11
B.22
C.99
D.121
E.171
I tried several different approaches any tried to input numbers to see how it reacts but nothing worked...
can someone care to explain? C_{old} = 90 + \frac{9Y_{old}}{11}Y_{old} = \frac{(C_{old} - 90)*11}{9}Y_{new} = \frac{(C_{old} + 99 - 90)*11}{9} = \frac{(C_{old} + 9)*11}{9}Increase = Y_{new} - Y_{old} = \frac{(C_{old} + 9)*11}{9} - \frac{(C_{old} - 90)*11}{9} = \frac{99*11}{9}= 121 Answer is D Ok so your thinking process was - i need to find an increase hence subtract Yold and Ynew. I did isolated Y and then instead of C i put C+99 but wasnt aware that i should treat them as Old and New. interesting...
_________________
If my answer helped, dont forget KUDOS!
IMPOSSIBLE IS NOTHING
|
|
|
|
|
|
GMAT Club team member
Joined: 02 Sep 2009
Posts: 11598
Followers: 1800
Kudos [?]:
9590
[0], given: 828
|
Re: In a certain economy, C represents the total amount of [#permalink]
15 Dec 2012, 05:54
roygush wrote: In a certain economy, C represents the total amount of consumption in millions of dollars, Y represents the total national income in millions of dollars, and the relationship between these two values is given by the equation C=90+9Y/11. If the total amount of consumption in the economy increases by 99 million dollars, what is the increase in the total national income, in millions of dollars?
A.11
B.22
C.99
D.121
E.171
I tried several different approaches any tried to input numbers to see how it reacts but nothing worked...
can someone care to explain? C=90+\frac{9Y}{11} --> Y=\frac{11C}{9}-9*11. Y_1=\frac{11C}{9}-9*11; Y_2=\frac{11(C+99)}{9}-9*11=\frac{11C}{9}+11*11-9*11=(\frac{11C}{9}-9*11)+121. Answer: D
_________________
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
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. NEW!!!
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. NEW!!!
What are GMAT Club Tests?
25 extra-hard Quant Tests
Find out what's new at GMAT Club - latest features and updates
|
|
|
|
|
|
SVP
Joined: 01 Sep 2010
Posts: 1747
Followers: 56
Kudos [?]:
582
[0], given: 467
|
Re: In a certain economy, C represents the total amount of [#permalink]
15 Dec 2012, 07:14
MacFauz wrote: roygush wrote: In a certain economy, C represents the total amount of consumption in millions of dollars, Y represents the total national income in millions of dollars, and the relationship between these two values is given by the equation C=90+9Y/11. If the total amount of consumption in the economy increases by 99 million dollars, what is the increase in the total national income, in millions of dollars?
A.11
B.22
C.99
D.121
E.171
I tried several different approaches any tried to input numbers to see how it reacts but nothing worked...
can someone care to explain? C_{old} = 90 + \frac{9Y_{old}}{11}Y_{old} = \frac{(C_{old} - 90)*11}{9}Y_{new} = \frac{(C_{old} + 99 - 90)*11}{9} = \frac{(C_{old} + 9)*11}{9}Increase = Y_{new} - Y_{old} = \frac{(C_{old} + 9)*11}{9} - \frac{(C_{old} - 90)*11}{9} = \frac{99*11}{9}= 121 Answer is D I like your approach step by step, is fine. But also if we do :C = 90 + 9y/11 ------> adding 99 we have 11 (C - 90 +99)/9= y -------> 11C + 99/9 = Y clearly the only value that fits is 11 * 2 + 99/9 = y. That is, 121
_________________
KUDOS is the good manner to help the entire community.
|
|
|
|
|
|
Intern
Joined: 24 Apr 2012
Posts: 44
Followers: 0
Kudos [?]:
7
[0], given: 1
|
Re: In a certain economy, C represents the total amount of [#permalink]
16 Dec 2012, 04:18
Ans: C = 90 + 9y/11 , adding 99 we have 11 (C - 90 +99)/9= y , (11C + 99)/9 = Y , so the increase is Y-y=121 the answer is (D).
_________________
www.mnemoniceducation.com
TURN ON YOUR MINDS!!!
|
|
|
|
|
|
|
Re: In a certain economy, C represents the total amount of
[#permalink]
16 Dec 2012, 04:18
|
|
|
|
|
|
|
|
|
|
|
close
