GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 15 Nov 2018, 23:39

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 in November
PrevNext
SuMoTuWeThFrSa
28293031123
45678910
11121314151617
18192021222324
2526272829301
Open Detailed Calendar
  • Free GMAT Strategy Webinar

     November 17, 2018

     November 17, 2018

     07:00 AM PST

     09:00 AM PST

    Nov. 17, 7 AM PST. Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.
  • GMATbuster's Weekly GMAT Quant Quiz # 9

     November 17, 2018

     November 17, 2018

     09:00 AM PST

     11:00 AM PST

    Join the Quiz Saturday November 17th, 9 AM PST. The Quiz will last approximately 2 hours. Make sure you are on time or you will be at a disadvantage.

The population of a certain town increases by 50 percent every 50 year

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

BSchool Thread Master
avatar
Joined: 19 Feb 2010
Posts: 350
The population of a certain town increases by 50 percent every 50 year  [#permalink]

Show Tags

New post 20 Sep 2010, 09:10
5
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

68% (01:46) correct 32% (01:41) wrong based on 212 sessions

HideShow timer Statistics

The population of a certain town increases by 50 percent every 50 years. If the population in 1950 was 810, in what year was the population 160?

A. 1650
B. 1700
C. 1750
D. 1800
E. 1850
Most Helpful Expert Reply
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 50615
Re: The population of a certain town increases by 50 percent every 50 year  [#permalink]

Show Tags

New post 20 Sep 2010, 09:20
3
2
cano wrote:
The population of a certain town increases by 50 percent every 50 years. If the population in 1950 was 810, in what year was the population 160?

A. 1650
B. 1700
C. 1750
D. 1800
E. 1850


Increase by 50% = times 1.5, so if the population at a certain year were 10 then in 50 years it would be 10*1.5 and in 50*2=100 years it would be 10*1.5*1.5=10*1.5^2 --> \(160*1.5^n=810\), where \(n\) is the # of 50-year periods --> \((\frac{3}{2})^n=\frac{81}{16}=(\frac{3}{2})^4\) --> \(n=4\), so there were 4 50-year periods --> 1950-4*50=1750.

Answer: C.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

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. ,11 Mixed Questions, 12 Fresh Meat

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., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

General Discussion
Senior Manager
Senior Manager
User avatar
Joined: 25 Feb 2010
Posts: 357
Re: The population of a certain town increases by 50 percent every 50 year  [#permalink]

Show Tags

New post 20 Sep 2010, 11:43
4 50 yrs to reach 810
_________________

GGG (Gym / GMAT / Girl) -- Be Serious

Its your duty to post OA afterwards; some one must be waiting for that...

Manager
Manager
User avatar
Joined: 29 Aug 2010
Posts: 154
Schools: Wharton/Lauder - Class of 2013
WE 1: Project Management, Telecommunications
Re: The population of a certain town increases by 50 percent every 50 year  [#permalink]

Show Tags

New post 20 Sep 2010, 12:42
3
I just worked this one backwards until I reached 160. If the population increases by 50% then you're multiplying the previous number by 3/2. So to work backwards, divide by 3/2 (which is the same as multiplying by 2/3).

So we have:

1950: 810
1900: 810*(2/3) = 540
1850: 540*(2/3) = 360
1800: 360*(2/3) = 240
1750: 240*(2/3) = 160

Answer is C
BSchool Thread Master
avatar
Joined: 19 Feb 2010
Posts: 350
Re: The population of a certain town increases by 50 percent every 50 year  [#permalink]

Show Tags

New post 20 Sep 2010, 16:50
redjam wrote:
I just worked this one backwards until I reached 160. If the population increases by 50% then you're multiplying the previous number by 3/2. So to work backwards, divide by 3/2 (which is the same as multiplying by 2/3).

So we have:

1950: 810
1900: 810*(2/3) = 540
1850: 540*(2/3) = 360
1800: 360*(2/3) = 240
1750: 240*(2/3) = 160

Answer is C


How long did it take you to work it like that?
Manager
Manager
avatar
Joined: 20 Jul 2010
Posts: 215
GMAT ToolKit User Reviews Badge
Re: The population of a certain town increases by 50 percent every 50 year  [#permalink]

Show Tags

New post 20 Sep 2010, 17:41
55 sec to work forward for C

160 -> 240 -> 360 -> 540 -> 810
_________________

If you like my post, consider giving me some KUDOS !!!!! Like you I need them

Manager
Manager
User avatar
Joined: 29 Aug 2010
Posts: 154
Schools: Wharton/Lauder - Class of 2013
WE 1: Project Management, Telecommunications
Re: The population of a certain town increases by 50 percent every 50 year  [#permalink]

Show Tags

New post 21 Sep 2010, 05:35
cano wrote:
How long did it take you to work it like that?


Didn't specifically time myself but it wasn't longer than 2 mins. I would say around 1.5 mins. They are all numbers easily divisible by 3.
EMPOWERgmat Instructor
User avatar
V
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 12863
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: The population of a certain town increases by 50 percent every 50 year  [#permalink]

Show Tags

New post 13 Feb 2017, 21:40
Hi All,

While this is an older prompt, it's still a great example of 'exponential growth', which is a concept that still appears on the GMAT occasionally. You can answer this question rather easily by TESTing THE ANSWERS.

We're told that a population increases by 50 percent every 50 years and that the population in 1950 was 810. We're asked to find the year in which the population was 160.

Let's TEST Answer B: 1700

IF....
the population was 160 in 1700 then...
the population was 240 in 1750 and...
the population was 360 in 1800 and...
the population was 540 in 1850 and...
the population was 810 in 1900

This is TOO EARLY (the population is supposed to hit 810 in 1950). Notice the pattern here though - if we just "shift" all of the values 50 years 'forward', then we'll hit 810 in 1950 (when the population in 1750 was 160).

Final Answer:

GMAT assassins aren't born, they're made,
Rich
_________________

760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save $75 + GMAT Club Tests Free
  Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

*****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!*****

Director
Director
User avatar
G
Joined: 23 Jan 2013
Posts: 570
Schools: Cambridge'16
Re: The population of a certain town increases by 50 percent every 50 year  [#permalink]

Show Tags

New post 17 Jul 2017, 20:13
equation is

160*(3/2)^x=810
(3/2)^x=5
x=4, so 50*4=200 years ago

C
Target Test Prep Representative
User avatar
G
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2830
Re: The population of a certain town increases by 50 percent every 50 year  [#permalink]

Show Tags

New post 20 Jul 2017, 15:51
cano wrote:
The population of a certain town increases by 50 percent every 50 years. If the population in 1950 was 810, in what year was the population 160?

A. 1650
B. 1700
C. 1750
D. 1800
E. 1850



We can create the following equation:

160(1.5)^n = 810

(3/2)^n = 810/160

(3/2)^n = 81/16

Since 3^4 = 81 and 2^4 = 16, we see that n must be 4 so that (3/2)^n = 81/16. However, here n represents the number of 50-year periods that it took for the population to increase from 160 to 810. Thus, the number of years was 4(50) = 200 for the population of 160 to reach a population of 810 in 1950. So, the population of 160 must have occurred in 1750.

Answer: C
_________________

Jeffery Miller
Head of GMAT Instruction

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 8779
Premium Member
Re: The population of a certain town increases by 50 percent every 50 year  [#permalink]

Show Tags

New post 26 Oct 2018, 21:13
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

GMAT Club Bot
Re: The population of a certain town increases by 50 percent every 50 year &nbs [#permalink] 26 Oct 2018, 21:13
Display posts from previous: Sort by

The population of a certain town increases by 50 percent every 50 year

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| 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®.