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

It is currently 18 Oct 2019, 05:21

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

The size of a certain population of bacteria doubles every 30 minutes

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

Hide Tags

Find Similar Topics 
Senior Manager
Senior Manager
User avatar
V
Joined: 25 Sep 2018
Posts: 426
Location: United States (CA)
Concentration: Finance, Strategy
GMAT 1: 640 Q47 V30
GPA: 3.97
WE: Investment Banking (Investment Banking)
CAT Tests
The size of a certain population of bacteria doubles every 30 minutes  [#permalink]

Show Tags

New post 08 Oct 2018, 12:15
1
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

61% (01:06) correct 39% (01:24) wrong based on 36 sessions

HideShow timer Statistics

The size of a certain population of bacteria doubles every 30 minutes. After 2 hours of growth, the size of the population will be what percent greater than the size of the population 2 hours earlier?

A) 15 percent
B)16 percent
C)1,500 percent
D) 1,600 percent
E) 1,700 percent

_________________
Why do we fall?...So we can learn to pick ourselves up again
Director
Director
avatar
G
Joined: 19 Oct 2013
Posts: 516
Location: Kuwait
GPA: 3.2
WE: Engineering (Real Estate)
GMAT ToolKit User
Re: The size of a certain population of bacteria doubles every 30 minutes  [#permalink]

Show Tags

New post 08 Oct 2018, 12:25
Abhi077 wrote:
The size of a certain population of bacteria doubles every 30 minutes. After 2 hours of growth, the size of the population will be what percent greater than the size of the population 2 hours earlier?

A) 15 percent
B)16 percent
C)1,500 percent
D) 1,600 percent
E) 1,700 percent


Say at the beginning it was x

Then at every 30 minutes interval it doubles.

1st 30 minutes 2*x
2nd 30 minutes 2*2*x
3rd 30 minutes interval 2*2*2*x
4th 30 minuts interval 2*2*2*2*x

In the form of 2^a for every 30 minutes.

Percentage increase (new-old)/old

16x-x = 15x/x = 15*100 = 1,500

Answer choice C.

Posted from my mobile device
Target Test Prep Representative
User avatar
D
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8099
Location: United States (CA)
Re: The size of a certain population of bacteria doubles every 30 minutes  [#permalink]

Show Tags

New post 10 Oct 2018, 18:46
1
Abhi077 wrote:
The size of a certain population of bacteria doubles every 30 minutes. After 2 hours of growth, the size of the population will be what percent greater than the size of the population 2 hours earlier?

A) 15 percent
B)16 percent
C)1,500 percent
D) 1,600 percent
E) 1,700 percent


Let’s say the size now is 10. The size would be 20 after 30 minutes, 40 after 60 minutes, 80 after 90 minutes, and 160 after 120 minutes, or 2 hours.

We use the percent increase formula: (New - Old)/Old x 100. Thus, the percent increase is:

(160 - 10)/10 x 100 = 15 x 100 = 1,500 percent

Answer: C
_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

GMAT Club Bot
Re: The size of a certain population of bacteria doubles every 30 minutes   [#permalink] 10 Oct 2018, 18:46
Display posts from previous: Sort by

The size of a certain population of bacteria doubles every 30 minutes

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





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