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

It is currently 22 Sep 2018, 13:55

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 youngest of 4 children has siblings who are 3, 5, and 8 years olde

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

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 49303
The youngest of 4 children has siblings who are 3, 5, and 8 years olde  [#permalink]

Show Tags

New post 13 Dec 2015, 06:07
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

89% (01:02) correct 11% (01:19) wrong based on 72 sessions

HideShow timer Statistics

The youngest of 4 children has siblings who are 3, 5, and 8 years older than she is. If the average (arithmetic mean) age of the 4 siblings is 21, what is the age of the youngest sibling?

A. 17
B. 18
C. 19
D. 21
E. 22

_________________

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

Board of Directors
User avatar
P
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4033
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User Premium Member
Re: The youngest of 4 children has siblings who are 3, 5, and 8 years olde  [#permalink]

Show Tags

New post 13 Dec 2015, 06:27
Bunuel wrote:
The youngest of 4 children has siblings who are 3, 5, and 8 years older than she is.


Let age of the youngest child be " y "

Age of the all the children in the family is y , (y + 3) ,(y + 5) and (y + 8)

Total age of all the children in the family is y + (y + 3) + (y + 5) + (y + 8) => 4y + 16

Bunuel wrote:
If the average (arithmetic mean) age of the 4 siblings is 21, what is the age of the youngest sibling?


Total age of the 4 sibling is 21 x 4 = 84 years ..

We already have the total age of alll the children is 4y + 16

So, 4y + 16 = 84

Or, 4y = 68

Or, y = 17

So, Age of the youngest child is 17 years.

_________________

Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )

Director
Director
User avatar
G
Joined: 20 Feb 2015
Posts: 733
Concentration: Strategy, General Management
Premium Member CAT Tests
Re: The youngest of 4 children has siblings who are 3, 5, and 8 years olde  [#permalink]

Show Tags

New post 13 Dec 2015, 12:16
let the youngest be Y
sum of ages of all the children = 4y+16=4*(avg)
4y+16=84
y=17
EMPOWERgmat Instructor
User avatar
V
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 12425
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: The youngest of 4 children has siblings who are 3, 5, and 8 years olde  [#permalink]

Show Tags

New post 14 Dec 2015, 17:57
Hi All,

This question can be solved by TESTing THE ANSWERS.

We're told that the YOUNGEST of 4 children has siblings who are 3, 5, and 8 years OLDER than she is and that the average age of the 4 siblings is 21. We're asked for the age of the youngest sibling.

Since the average age is 21 and we're trying to figure out the age of the YOUNGEST sibling, we should look for an answer that is several years LESS than 21...

Let's TEST Answer B: 18 years

IF...
Youngest = 18
Siblings = 21, 23 and 26
Sum = 88
Average = 88/4 = 22
This is TOO HIGH (the average is supposed to be 21).

Since the average is too high, all 4 of the children are TOO OLD. There's only one answer left that would lower the average...

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!***********************

Current Student
avatar
Joined: 02 Jun 2015
Posts: 84
Location: Brazil
Concentration: Entrepreneurship, General Management
GPA: 3.3
Re: The youngest of 4 children has siblings who are 3, 5, and 8 years olde  [#permalink]

Show Tags

New post 15 Dec 2015, 12:45
Testing the answer in my opinion takes a long time.

We know that each one is 3,5,8 years OLDER

X + (3+X) + (5+X) + (8+X) = 21*4
4X + 16 = 84
4X = 68
X = 17
EMPOWERgmat Instructor
User avatar
V
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 12425
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: The youngest of 4 children has siblings who are 3, 5, and 8 years olde  [#permalink]

Show Tags

New post 15 Dec 2015, 16:55
Hi douglasvg,

If you're not using Tactics (such as TEST THE ANSWERS) very often, then it might take you a little longer to use that approach right now (since you're not used to thinking in that way). However, in the long run - and on harder questions - those same Tactics can be extremely valuable.

1) How have you been scoring on your practice CATs (including the Quant and Verbal Scaled Scores)?
2) How is your pacing in the Quant section? Do you have to rush just to finish?

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!***********************

Current Student
avatar
Joined: 02 Jun 2015
Posts: 84
Location: Brazil
Concentration: Entrepreneurship, General Management
GPA: 3.3
Re: The youngest of 4 children has siblings who are 3, 5, and 8 years olde  [#permalink]

Show Tags

New post 15 Dec 2015, 17:06
EMPOWERgmatRichC wrote:
Hi douglasvg,

If you're not using Tactics (such as TEST THE ANSWERS) very often, then it might take you a little longer to use that approach right now (since you're not used to thinking in that way). However, in the long run - and on harder questions - those same Tactics can be extremely valuable.

1) How have you been scoring on your practice CATs (including the Quant and Verbal Scaled Scores)?
2) How is your pacing in the Quant section? Do you have to rush just to finish?

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

On GMATPREP software Im scoring between 45-50 in quant
For hard question I indeed use it, then its a fast way to solve it.

Thank you Empower :-D
CEO
CEO
User avatar
D
Joined: 12 Sep 2015
Posts: 2878
Location: Canada
The youngest of 4 children has siblings who are 3, 5, and 8 years olde  [#permalink]

Show Tags

New post 09 Jan 2018, 10:12
Top Contributor
Bunuel wrote:
The youngest of 4 children has siblings who are 3, 5, and 8 years older than she is. If the average (arithmetic mean) age of the 4 siblings is 21, what is the age of the youngest sibling?

A. 17
B. 18
C. 19
D. 21
E. 22


Let y = the age of the youngest child

So, y + 3 = age of sibling who is 3 years older than the youngest child
y + 5 = age of sibling who is 5 years older than the youngest child
y + 8 = age of sibling who is 8 years older than the youngest child

The average (arithmetic mean) age of the 4 siblings is 21
This means: [y + (y+3) + (y+5) + (y+8)]/4 = 21
Multiply both sides by 4 to get: y + (y+3) + (y+5) + (y+8) = 84
Simplify: 4y + 16 = 84
Solve: y = 17

Answer: A

Cheers,
Brent
_________________

Brent Hanneson – GMATPrepNow.com
Image
Sign up for our free Question of the Day emails

Intern
Intern
avatar
B
Joined: 15 Aug 2017
Posts: 15
Re: The youngest of 4 children has siblings who are 3, 5, and 8 years olde  [#permalink]

Show Tags

New post 10 Jan 2018, 01:31
1
X + (3+X) + (5+X) + (8+X) = 21*4
4 X + 16 = 84
4 X = 68
X = 17
Target Test Prep Representative
User avatar
G
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2835
Re: The youngest of 4 children has siblings who are 3, 5, and 8 years olde  [#permalink]

Show Tags

New post 30 Jul 2018, 11:33
Bunuel wrote:
The youngest of 4 children has siblings who are 3, 5, and 8 years older than she is. If the average (arithmetic mean) age of the 4 siblings is 21, what is the age of the youngest sibling?

A. 17
B. 18
C. 19
D. 21
E. 22


We can let x = the age of the youngest child; thus, the ages of the three older children are x + 3, x + 5 and x + 8, respectively. We can create the equation:

(x + x + 3 + x + 5 + x + 8)/4 = 21

4x + 16 = 84

4x = 68

x = 17

Answer: A
_________________

Jeffery Miller
Head of GMAT Instruction

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

GMAT Club Bot
Re: The youngest of 4 children has siblings who are 3, 5, and 8 years olde &nbs [#permalink] 30 Jul 2018, 11:33
Display posts from previous: Sort by

The youngest of 4 children has siblings who are 3, 5, and 8 years olde

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

Events & Promotions

PREV
NEXT


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®.