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.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

0% (00:00) correct
0% (00:00) wrong based on 1 sessions

HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

How would you solve?

A scientist is studying bacteria whose cell population doubles at constant intervals, at which times each cell in the population divides simultaneously. Four hours from now, immediately after the population doubles, the scientist will destroy the entire sample. How many cells will the population contain when the bacteria is destroyed?

(1) Since the population divided two hours ago, the population has quadrupled, increasing by 3,750 cells.

(2) The population will double to 40,000 cells with one hour remaining until the scientist destroys the sample.

(1) Since the population divided two hours ago, the population has quadrupled, increasing by 3,750 cells.

(2) The population will double to 40,000 cells with one hour remaining until the scientist destroys the sample.

Need 2 more pieces of info to solve problem:
How often does the population double?
What is the pop. size immediately following the doubling of a population?

(1) If there was a quadrupling of the pop. in last 2 hrs, this means that the pop. doubled 2X in that time span - not necessarily meaning that the doubling occurred in 60 min. intervals. Since the frequency of the population's doubling cannot be determined here, this is - INSUFFICIENT

(2) No info on the frequency of the population's doubling - INSUFFICIENT

Try combining:
(1) cells divided 2 hrs ago
4x = x + 3750
3x = 3750
x = 1250

Since the pop. doubled to 1250 cells exactly 2 hrs ago and will multiply 2X to 40k cells in 3 hrs, the frequency is established.

statement one tells us 1: that *two hours ago the cells divided* (so we have a reference point to calculate future divisions- remeber they divide at a constant rate) it goes on to tell us that 2: it has quadrupled in the past two hours since that division, so we know it doubles every hour. it also tells us the amount of the increase due to the quadrupling. I am too tired to calculate the population, but I know this is all the info we need, since they divide at a constant rate, to figure out what the population will be in 4 hours.

statement II: doesn't give us a starting point to figure out how often the cells divide.