It is currently 22 Feb 2018, 20:39

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.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

AMOUNT OF BACTERIA PRESENT Time Amount 1:00 P.M. 10.0 grams

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Senior Manager
Senior Manager
avatar
Joined: 02 Dec 2007
Posts: 448
AMOUNT OF BACTERIA PRESENT Time Amount 1:00 P.M. 10.0 grams [#permalink]

Show Tags

New post 08 Sep 2008, 04:47
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

AMOUNT OF BACTERIA PRESENT
Time Amount
1:00 P.M. 10.0 grams
4:00 P.M. x grams
7:00 P.M. 14.4 grams

Data for a certain biology experiment are given in the table above. If the amount of bacteria present increased by the same fraction during each of the two 3-hour periods shown, how many grams of bacteria were present at 4:00 P.M.?

A. 12.0
B. 12.1
C. 12.2
D. 12.3
E. 12.4

guys can anyone provide a short approach to this one without using quadratic equations or plugging answers ?
thanks in advance
Intern
Intern
avatar
Joined: 19 Aug 2008
Posts: 1
Re: short approach [#permalink]

Show Tags

New post 08 Sep 2008, 06:12
Let the amount of increase from 1-4pm and 4-7pm be y.

The equations can be written as
10+y=x - (1)
x+y=14.4 - (2)

Solving the 2 equations we get x=12.2

Answer C.
SVP
SVP
User avatar
Joined: 29 Aug 2007
Posts: 2467
Re: short approach [#permalink]

Show Tags

New post 08 Sep 2008, 07:32
Nihit wrote:
AMOUNT OF BACTERIA PRESENT
Time Amount
1:00 P.M. 10.0 grams
4:00 P.M. x grams
7:00 P.M. 14.4 grams

Data for a certain biology experiment are given in the table above. If the amount of bacteria present increased by the same fraction during each of the two 3-hour periods shown, how many grams of bacteria were present at 4:00 P.M.?

A. 12.0
B. 12.1
C. 12.2
D. 12.3
E. 12.4

guys can anyone provide a short approach to this one without using quadratic equations or plugging answers ? thanks in advance


x/10 = 14.4/x
x = 12

A.
_________________

Verbal: http://gmatclub.com/forum/new-to-the-verbal-forum-please-read-this-first-77546.html
Math: http://gmatclub.com/forum/new-to-the-math-forum-please-read-this-first-77764.html
Gmat: http://gmatclub.com/forum/everything-you-need-to-prepare-for-the-gmat-revised-77983.html


GT

SVP
SVP
User avatar
Joined: 07 Nov 2007
Posts: 1789
Location: New York
Re: short approach [#permalink]

Show Tags

New post 08 Sep 2008, 07:46
Nihit wrote:
AMOUNT OF BACTERIA PRESENT
Time Amount
1:00 P.M. 10.0 grams
4:00 P.M. x grams
7:00 P.M. 14.4 grams

Data for a certain biology experiment are given in the table above. If the amount of bacteria present increased by the same fraction during each of the two 3-hour periods shown, how many grams of bacteria were present at 4:00 P.M.?

A. 12.0
B. 12.1
C. 12.2
D. 12.3
E. 12.4

guys can anyone provide a short approach to this one without using quadratic equations or plugging answers ?
thanks in advance


(x-10)/10 =(14.4-x)/x
x*x=144
x=12
A
_________________

Your attitude determines your altitude
Smiling wins more friends than frowning

Senior Manager
Senior Manager
User avatar
Joined: 04 Jan 2006
Posts: 276
Re: short approach [#permalink]

Show Tags

New post 08 Sep 2008, 07:50
Nihit wrote:
AMOUNT OF BACTERIA PRESENT
Time Amount
1:00 P.M. 10.0 grams
4:00 P.M. x grams
7:00 P.M. 14.4 grams

Data for a certain biology experiment are given in the table above. If the amount of bacteria present increased by the same fraction during each of the two 3-hour periods shown, how many grams of bacteria were present at 4:00 P.M.?

A. 12.0
B. 12.1
C. 12.2
D. 12.3
E. 12.4

guys can anyone provide a short approach to this one without using quadratic equations or plugging answers ?
thanks in advance


My approach is the same as that above me.

(Time,Amount)
(0,10)
(3, 10x)
(6,10x^2)

Since
10(x^2) = 14.4
100(x^2) = 144 ---------- x 10
x^2 = 144/100
|x| = 12/10 ---------- sqrt
x = +1.2, -1.2

x can only be positive. Therefore, the amount of bacteria at 4:00PM = 10*1.2 = 12

A
SVP
SVP
avatar
Joined: 17 Jun 2008
Posts: 1529
Re: short approach [#permalink]

Show Tags

New post 09 Sep 2008, 10:14
What is the OA?

Does "increase by same fraction" mean the ratio? To me, this means the difference and not the fraction and with this logic, x - 10 = 14.4 - x => x = 12.2

Am I interpreting something wrong here?
Manager
Manager
avatar
Joined: 03 Jun 2008
Posts: 135
Schools: ISB, Tuck, Michigan (Ross), Darden, MBS
Re: short approach [#permalink]

Show Tags

New post 09 Sep 2008, 10:21
Nihit wrote:
AMOUNT OF BACTERIA PRESENT
Time Amount
1:00 P.M. 10.0 grams
4:00 P.M. x grams
7:00 P.M. 14.4 grams

Data for a certain biology experiment are given in the table above. If the amount of bacteria present increased by the same fraction during each of the two 3-hour periods shown, how many grams of bacteria were present at 4:00 P.M.?

A. 12.0
B. 12.1
C. 12.2
D. 12.3
E. 12.4

guys can anyone provide a short approach to this one without using quadratic equations or plugging answers ?
thanks in advance


The best way to solve this should be thru options.

Taking first option: 12

So from 10 to 12.. the percentage increase is 20 percent.

Similarly, from 12 to 14.4 the percentage increase is 20 percent.

SInce its the same percentage increase in both the cases, A has to be the answer.
_________________

-----------------------------------------------------------
'It's not the ride, it's the rider'

Re: short approach   [#permalink] 09 Sep 2008, 10:21
Display posts from previous: Sort by

AMOUNT OF BACTERIA PRESENT Time Amount 1:00 P.M. 10.0 grams

  post reply Question banks Downloads My Bookmarks Reviews Important topics  

Moderator: chetan2u



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

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.