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.
May 1410:00 AM PDT
-11:00 AM PDT
GMAT Verbal Practice question quiz. Solve 20 GMAT Focus practice questions written by GMAT Ninja. Take this GMAT practice test live with peers in timed conditions, analyze your GMAT study progress, and see where you stand in the GMAT student pool.
May 1411:30 AM EDT
-12:30 PM EDT
Is INSEAD your dream b-school and you're looking for solid prep and application strategies to get there? Check out Barkavi’s end-to-end journey to know how she did! Get insights into the INSEAD admissions process, know what Adcoms look at, and more!- May 15
08:30 AM PDT
-09:30 AM PDT
Struggling with Boldface or Paradox questions in GMAT Critical Reasoning (CR)? Boldface and Paradox CR questions are often overlooked amidst the other more common GMAT CR question types. But mastering these can significantly boost your Verbal score. - May 15
10:00 AM PDT
-11:00 AM PDT
Struggling to finish the GMAT on time? You’re not alone. The #1 reason students score lower than expected on the GMAT isn’t lack of knowledge or silly mistakes—it’s running out of time. 
May 1609:00 PM PDT
-10:00 PM PDT
Full-length FE mock with insightful analytics, weakness diagnosis, and video explanations!
May 1706:30 AM PDT
-08:30 AM PDT
We know Strengthen and Weaken questions account for more than 50% of the CR questions on the GMAT. With CR becoming even more important on GMAT Focus, it's time you strengthen your weaknesses with an approach that improves your solving time and accuracy!
May 1711:00 AM IST
-01:00 PM IST
Attend this session to learn how to Deconstruct arguments, Pre-Think Author’s Assumptions, and apply Negation Test.- May 18
11:00 AM IST
-01:00 PM IST
Attend this free GMAT Algebra Webinar and learn how to master the most challenging Inequalities and Absolute Value problems with ease. - Jun 10
06:00 AM PDT
-05:30 PM PDT
Register for the GMAT Club Virtual MBA Spotlight fair, the biggest MBA fair of the year. You will have a chance to hear Admissions directors from almost every Top 20 program speak, network with peers, and conveniently attend morning or afternoon sessions.
16 Sep 2014, 00:48
Kudos
Bookmarks
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
45%
(medium)
Question Stats:
71% (01:53) correct
29%
(02:36)
wrong
based on 72
sessions
History
Date
Time
Result
Not Attempted Yet
If a bacterial colony doubles every day at 9 a.m. and loses 320 bacteria every day at 9 p.m., what was the population size of the colony at 8 a.m. on Day 3 if exactly 320 bacteria were lost at 9 p.m. on Day 5, resulting in extinction of the colony?
A. 160
B. 240
C. 280
D. 480
E. 560
A. 160
B. 240
C. 280
D. 480
E. 560
16 Sep 2014, 00:48
Kudos
Bookmarks
Official Solution:
If a bacterial colony doubles every day at 9 a.m. and loses 320 bacteria every day at 9 p.m., what was the population size of the colony at 8 a.m. on Day 3 if exactly 320 bacteria were lost at 9 p.m. on Day 5, resulting in extinction of the colony?
A. 160
B. 240
C. 280
D. 480
E. 560
Suppose the size of the colony at 8 a.m. on Day 3 was \(x\) bacteria;
At 9 a.m. on Day 3 it would become \(2x\) and at 9 p.m. of the same day it would become \(2x - 320\);
At 9 a.m. on Day 4 it would become \(2(2x - 320)\) and at 9 p.m. of the same day it would become \(2(2x - 320) - 320\);
At 9 a.m. on Day 5 it would become \(2*(2(2x - 320) - 320)\) and at 9 p.m. of the same day it would become \(2*(2(2x - 320) - 320) - 320\);
Since at that point the colony was extinct, then \(2*(2(2x - 320) - 320) - 320=0\).
Solving gives \(x = 280\)
Answer: C
If a bacterial colony doubles every day at 9 a.m. and loses 320 bacteria every day at 9 p.m., what was the population size of the colony at 8 a.m. on Day 3 if exactly 320 bacteria were lost at 9 p.m. on Day 5, resulting in extinction of the colony?
A. 160
B. 240
C. 280
D. 480
E. 560
Suppose the size of the colony at 8 a.m. on Day 3 was \(x\) bacteria;
At 9 a.m. on Day 3 it would become \(2x\) and at 9 p.m. of the same day it would become \(2x - 320\);
At 9 a.m. on Day 4 it would become \(2(2x - 320)\) and at 9 p.m. of the same day it would become \(2(2x - 320) - 320\);
At 9 a.m. on Day 5 it would become \(2*(2(2x - 320) - 320)\) and at 9 p.m. of the same day it would become \(2*(2(2x - 320) - 320) - 320\);
Since at that point the colony was extinct, then \(2*(2(2x - 320) - 320) - 320=0\).
Solving gives \(x = 280\)
Answer: C
23 Feb 2023, 08:11
Kudos
Bookmarks
I have edited the question and the solution by adding more details to enhance its clarity. I hope it is now easier to understand.
