It is currently 28 Jun 2017, 10:24

# Live Now:

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Cost is expressed by the formula tb^4

Author Message
TAGS:

### Hide Tags

Manager
Joined: 13 Jul 2013
Posts: 73
GMAT 1: 570 Q46 V24
Cost is expressed by the formula tb^4 [#permalink]

### Show Tags

07 Sep 2013, 22:24
1
This post was
BOOKMARKED
00:00

Difficulty:

15% (low)

Question Stats:

75% (01:57) correct 25% (01:04) wrong based on 64 sessions

### HideShow timer Statistics

Cost is expressed by the formula tb^4. If b is doubled, the new cost is what percent of the original cost?

(A) 200
(B) 600
(C) 800
(D) 1600
(E) 50

I read the explanation in Manhattan but cant relate to it.

I worked it out this way

Assume,
t=1
b=2

Original = (1*2)^4= 16
New= (1*2*2)^4 = 256

% change= (change/Original)*100
=(240/16)*100
=1500

Where am I going wrong?

Thanks
[Reveal] Spoiler: OA
Verbal Forum Moderator
Joined: 10 Oct 2012
Posts: 629
Re: Cost is expressed by the formula tb^4 [#permalink]

### Show Tags

07 Sep 2013, 22:30
1
KUDOS
theGame001 wrote:
Cost is expressed by the formula tb^4. If b is doubled, the new cost is what percent
of the original cost?

(A) 200
(B) 600
(C)800
(D) 1600
(E) 50

I read the explanation in Manhattan but cant relate to it.

I worked it out this way

Assume,
t=1
b=2

Original = (1*2)^4= 16
New= (1*2*2)^4 = 256

% change= (change/Original)*100
=(240/16)*100
=1500

Where am I going wrong?

Thanks

The question asks for the relative percent b/w the new cost and the final cost, that is $$\frac{256}{16}*100$$ and NOT the precent increase/decrease.

For example, initial cost=1 , final cost = 2, and the question asks what percent of the original cost is the final cost : $$\frac{2}{1}*100$$ = 200%

Again, if the question asks, what is the percent increase between the final and the initial cost : $$\frac{2-1}{1}*100$$ = 100%
_________________
Intern
Joined: 14 Aug 2013
Posts: 35
Location: United States
Concentration: Finance, Strategy
GMAT Date: 10-31-2013
GPA: 3.2
WE: Consulting (Consumer Electronics)
Re: Cost is expressed by the formula tb^4 [#permalink]

### Show Tags

07 Sep 2013, 22:56
1
KUDOS
theGame001 wrote:
Cost is expressed by the formula tb^4. If b is doubled, the new cost is what percent
of the original cost?

(A) 200
(B) 600
(C)800
(D) 1600
(E) 50

I read the explanation in Manhattan but cant relate to it.

I worked it out this way

Assume,
t=1
b=2

Original = (1*2)^4= 16
New= (1*2*2)^4 = 256

% change= (change/Original)*100
=(240/16)*100
=1500

Where am I going wrong?

Thanks

Original Cost C1=t1*b1^4
New Cost C2=t2*b2^4....only b is doubled so t2=t1 and b2=2b1
C2=t2*(2b1)^4
=16(t1*b1^4)
=16C1
16 times C1=>1600% of C1
Ans D=1600
Manager
Joined: 26 Feb 2013
Posts: 177
Re: Cost is expressed by the formula tb^4 [#permalink]

### Show Tags

08 Sep 2013, 00:23
I thought we need to multiply b^4 and did 2(b^4) and answered wrong.
Manager
Joined: 13 Jul 2013
Posts: 73
GMAT 1: 570 Q46 V24
Re: Cost is expressed by the formula tb^4 [#permalink]

### Show Tags

08 Sep 2013, 02:15
mau5 wrote:
theGame001 wrote:
Cost is expressed by the formula tb^4. If b is doubled, the new cost is what percent
of the original cost?

(A) 200
(B) 600
(C)800
(D) 1600
(E) 50

I read the explanation in Manhattan but cant relate to it.

I worked it out this way

Assume,
t=1
b=2

Original = (1*2)^4= 16
New= (1*2*2)^4 = 256

% change= (change/Original)*100
=(240/16)*100
=1500

Where am I going wrong?

Thanks

The question asks for the relative percent b/w the new cost and the final cost, that is $$\frac{256}{16}*100$$ and NOT the precent increase/decrease.

For example, initial cost=1 , final cost = 2, and the question asks what percent of the original cost is the final cost : $$\frac{2}{1}*100$$ = 200%

Again, if the question asks, what is the percent increase between the final and the initial cost : $$\frac{2-1}{1}*100$$ = 100%

Ahhhh, okay. Thanks, I clearly misinterpreted the question.
Math Expert
Joined: 02 Sep 2009
Posts: 39750
Re: Cost is expressed by the formula tb^4 [#permalink]

### Show Tags

08 Sep 2013, 04:45
theGame001 wrote:
Cost is expressed by the formula tb^4. If b is doubled, the new cost is what percent of the original cost?

(A) 200
(B) 600
(C) 800
(D) 1600
(E) 50

I read the explanation in Manhattan but cant relate to it.

I worked it out this way

Assume,
t=1
b=2

Original = (1*2)^4= 16
New= (1*2*2)^4 = 256

% change= (change/Original)*100
=(240/16)*100
=1500

Where am I going wrong?

Thanks

The point is that 16tb^4 is 1600% of tb^4 but 16tb^4 is 1500% greater than tb^4.
_________________
Re: Cost is expressed by the formula tb^4   [#permalink] 08 Sep 2013, 04:45
Similar topics Replies Last post
Similar
Topics:
9 If the expression x^x^x^(...), where the given expression expression 6 31 Jan 2017, 06:11
8 If the Area of a Triangle ABC is given by the formula 7 26 Dec 2013, 15:26
1 The cost C of manufacturing a product can be estimated by the formula 15 19 Dec 2014, 14:09
15 In a certain formula, p is directly proportional to s and 6 26 Dec 2016, 15:46
56 In a certain company, the formula for maximizing profits is 18 07 Mar 2016, 08:33
Display posts from previous: Sort by