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

 It is currently 17 Sep 2019, 18:06

### 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

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

# The average of the five numbers is 6.8. If one of the numbers is multi

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 58037
The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

08 Apr 2015, 05:16
3
14
00:00

Difficulty:

45% (medium)

Question Stats:

64% (01:39) correct 36% (01:35) wrong based on 275 sessions

### HideShow timer Statistics

The average of the five numbers is 6.8. If one of the numbers is multiplied by 3, the average of the numbers increases to 9.2. Which of the five numbers is multiplied by 3?

(A) 1.5
(B) 3.0
(C) 3.9
(D) 4.0
(E) 6.0

Kudos for a correct solution.

_________________
Manager
Joined: 17 Mar 2015
Posts: 115
The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

08 Apr 2015, 05:54
4
1
Or we can just do some very easy algebra.
$$a_1 + a_2 + a_3 + a_4 + a_5 = 34$$(1)
lets say first number was multiplied by 3
$$3*a_1 + a_2 + a_3 + a_4 + a_5 = 46$$ (2)
subtract (2) from (1), $$2*a_1 = 12, a1 = 6$$
Option E
##### General Discussion
Manager
Joined: 17 Nov 2013
Posts: 72
Concentration: Strategy, Healthcare
GMAT 1: 710 Q49 V38
GPA: 3.34
Re: The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

08 Apr 2015, 05:23
2
1
Initial avg is 6.8
So the summation of the nos is 6.8*5 = 34

Now the new avg is 9.2
So summation will be 9.2*5 = 46.
So change in summation is 12.
This comes when a number is multiplied by 3.
In the original sum we already have that number added once. To bring additional 12 increment by multiplying by 3, we get a total increase of 18. Thus, 6 is multiplied by 3.

We can also do trial and error on all nos and see the knw tht gives 12 increase.

Posted from GMAT ToolKit
_________________
Current Student
Joined: 23 May 2013
Posts: 184
Location: United States
Concentration: Technology, Healthcare
GMAT 1: 760 Q49 V45
GPA: 3.5
The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

08 Apr 2015, 09:29
3
Bunuel wrote:
The average of the five numbers is 6.8. If one of the numbers is multiplied by 3, the average of the numbers increases to 9.2. Which of the five numbers is multiplied by 3?

(A) 1.5
(B) 3.0
(C) 3.9
(D) 4.0
(E) 6.0

Kudos for a correct solution.

$$x_1 + x_2 + x_3 + x_4 + x_5 = 5*(6.8) = 34$$

$$3x_1 +x_2 + x_3 + x_4 + x_5 = 5*(9.2) = 46$$

Subtract the first from the second:

$$2x_1 = 12$$

$$x_1 = 6.$$

Manager
Joined: 03 Sep 2014
Posts: 75
Concentration: Marketing, Healthcare
Re: The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

08 Apr 2015, 13:03
2
1
Bunuel wrote:
The average of the five numbers is 6.8. If one of the numbers is multiplied by 3, the average of the numbers increases to 9.2. Which of the five numbers is multiplied by 3?

(A) 1.5
(B) 3.0
(C) 3.9
(D) 4.0
(E) 6.0

Kudos for a correct solution.

Let X = {x1,x2,x3,x4,x5}

Sum(X) = 6.8*5 = 34

Let y be the no. that is multiplied by 3

Thus, Sum(X) - y +y*3 = 9.2*5

=> 34 +2y = 46 => 2y = 12 => y = 6

Manager
Joined: 26 Dec 2012
Posts: 145
Location: United States
Concentration: Technology, Social Entrepreneurship
WE: Information Technology (Computer Software)
Re: The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

08 Apr 2015, 14:43
2
Equation 1: a+b+c+d+e=6.8*5=34
Equation 2: 3a+b+c+d+e=9.2*5=46
Deducting equation 1 from 2 we get : 2a=46-34=12=>a=6

Thanks,
Intern
Joined: 20 Nov 2013
Posts: 25
Schools: LBS '17
Re: The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

09 Apr 2015, 03:28
1

a+b+c+d+e = 6.8 * 5
3a+b+c+d+e = 9.2*5

by subtracting the two equations we get
2a = 12 thus a = 6
Math Expert
Joined: 02 Sep 2009
Posts: 58037
Re: The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

13 Apr 2015, 06:13
Bunuel wrote:
The average of the five numbers is 6.8. If one of the numbers is multiplied by 3, the average of the numbers increases to 9.2. Which of the five numbers is multiplied by 3?

(A) 1.5
(B) 3.0
(C) 3.9
(D) 4.0
(E) 6.0

Kudos for a correct solution.

VERITAS PREP OFFICIAL SOLUTION:

You can do this problem in a few different ways, but perhaps the best way is Algebra! No matter how you choose the address the question you will need to determine the magnitude of the increase. Since “sum (total) = average * # of terms” You can take the average of 6.8 times the five terms and get a beginning total of 34. The new total is 9.2 times 5 which equals 46. So the increase is 12.

In order to create an equation you need to ask yourself “what happened to cause that increase of 12?” The question stem tells you that one of the numbers was multiplied by 3. So when one of the numbers (we can call that number “x”) was multiplied by 3 the total increased by 12.

The equation formed from this information is simply “3x = x + 12.” The “3x” is because the number is multiplied by 3 and the “x + 12” is because you had the x to start with (there were five numbers right? and x was one of them) and you added 12 because of the increase to the sum.

So if “3x = x + 12” then x = 6. So the correct answer is E.

This question can be done based on knowledge of number properties and can even be done by working directly with the answer choices. However, neither of these methods is as reliable for most students as the algebra is. I have worked with the question for years and I can tell you that more people choose D than choose the correct answer. Yet very few of the people who get this wrong used algebra. Those who use algebra generally seem to get this question right.

Make sure that you are very comfortable with algebra, after all, bringing your “A Game” is essential to your success on the Quant section!
_________________
Current Student
Joined: 12 Aug 2015
Posts: 2594
Schools: Boston U '20 (M)
GRE 1: Q169 V154
Re: The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

08 Aug 2017, 00:07
Excellent Question.
Here is what I did on this question =>
Sum (initial) => 5*6.8 => 34
Sum (final) => 5*9.2 => 46

Now difference => 12

Let p be the number multiplied by 3.

p => 3p

Thus we added 2p to the list.

Therefore => 2p = 12

Thus p = 6

Hence D.

_________________
Manager
Joined: 13 Nov 2018
Posts: 108
Location: India
GMAT 1: 700 Q51 V32
Re: The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

19 Nov 2018, 14:00
Bunuel wrote:
The average of the five numbers is 6.8. If one of the numbers is multiplied by 3, the average of the numbers increases to 9.2. Which of the five numbers is multiplied by 3?

(A) 1.5
(B) 3.0
(C) 3.9
(D) 4.0
(E) 6.0

Kudos for a correct solution.

this is pretty good question

x1+x2+x3+x4+x5=5∗(6.8)=34x1+x2+x3+x4+x5=5∗(6.8)=34

3x1+x2+x3+x4+x5=5∗(9.2)=463x1+x2+x3+x4+x5=5∗(9.2)=46

Subtract the first from the second:

-After subtracting above average we will get 12
till this step i understood

then i divided by 3 i got answer 4 and not 6

where i got wrong??
Manager
Joined: 14 Jun 2018
Posts: 219
The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

20 Nov 2018, 05:13
gmatdordie wrote:
Bunuel wrote:
The average of the five numbers is 6.8. If one of the numbers is multiplied by 3, the average of the numbers increases to 9.2. Which of the five numbers is multiplied by 3?

(A) 1.5
(B) 3.0
(C) 3.9
(D) 4.0
(E) 6.0

Kudos for a correct solution.

this is pretty good question

x1+x2+x3+x4+x5=5∗(6.8)=34x1+x2+x3+x4+x5=5∗(6.8)=34

3x1+x2+x3+x4+x5=5∗(9.2)=463x1+x2+x3+x4+x5=5∗(9.2)=46

Subtract the first from the second:

-After subtracting above average we will get 12
till this step i understood

then i divided by 3 i got answer 4 and not 6

where i got wrong??

you need to divide by 2 , not 3

3x1 - x1 = 2x1 = 12 ; x1 = 6
and assume better variables. That was really hard to look at
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 9640
Location: Pune, India
Re: The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

20 Nov 2018, 05:36
Bunuel wrote:
The average of the five numbers is 6.8. If one of the numbers is multiplied by 3, the average of the numbers increases to 9.2. Which of the five numbers is multiplied by 3?

(A) 1.5
(B) 3.0
(C) 3.9
(D) 4.0
(E) 6.0

Kudos for a correct solution.

When you increase a number (by multiplying it by 3), the avg goes from 6.8 to 9.2 i.e. an increase of 2.4 in all 5 numbers.
This is a total increase of 2.4*5 = 12

This 12 represents twice the original number because when we multiply a number by 3, we add twice the number to it. So original number is 12/2 = 6

Check out the following blog posts on Veritas Prep website:
https://www.veritasprep.com/blog/2012/0 ... etic-mean/
https://www.veritasprep.com/blog/2012/0 ... questions/
https://www.veritasprep.com/blog/2012/0 ... eviations/
https://www.veritasprep.com/blog/2012/0 ... tic-means/
_________________
Karishma
Veritas Prep GMAT Instructor

Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 7729
Location: United States (CA)
Re: The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

24 Aug 2019, 05:30
1
Bunuel wrote:
The average of the five numbers is 6.8. If one of the numbers is multiplied by 3, the average of the numbers increases to 9.2. Which of the five numbers is multiplied by 3?

(A) 1.5
(B) 3.0
(C) 3.9
(D) 4.0
(E) 6.0

Kudos for a correct solution.

The sum of the original 5 numbers is 6.8 x 5 = 34.

If we let k = the number that is multiplied by a factor of 3, then the new sum is 34 - k + 3k = 34 + 2k. We can create the equation:

(34 + 2k)/5 = 9.2

34 + 2k = 46

2k = 12

k = 6

_________________

# Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
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.

VP
Joined: 07 Dec 2014
Posts: 1233
The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

24 Aug 2019, 20:03
Bunuel wrote:
The average of the five numbers is 6.8. If one of the numbers is multiplied by 3, the average of the numbers increases to 9.2. Which of the five numbers is multiplied by 3?

(A) 1.5
(B) 3.0
(C) 3.9
(D) 4.0
(E) 6.0

let t=original total
n=original number
eq1: t=5*6.8
eq2: t+2n=5*9.2
subtracting eq1 from eq2,
n=6.0
E
Senior Manager
Joined: 29 Jun 2019
Posts: 304
Re: The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

24 Aug 2019, 20:47
a1+....=34=(5*6.8)
3a1+....=46=(5*9.2)
3a1-a1=12
2a1=12
a1=6
Option E

Posted from my mobile device
_________________
Always waiting
Senior Manager
Joined: 10 Aug 2018
Posts: 314
Location: India
Concentration: Strategy, Operations
WE: Operations (Energy and Utilities)
Re: The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

24 Aug 2019, 21:13

x+y=6.8*5 ====> x+y=34
x+3y=9.2*5 ====> x+3y=46

solving the two equations for y we get y=6.
y is the number that is multiplied by 3.
_________________
Don't forget to give KUDOS.
On the way to conquer the GMAT and I will not leave it until I win. WHATEVER IT TAKES.
Target 720+

" I CAN AND I WILL"

1) Gmat prep: [620 Q48 V27], 2) Gmat prep: [610 Q47 V28], 3) Gmat prep: [620 Q47 V28],
4) Gmat prep: [660 Q47 V34], 5) Gmat prep: [560 Q37 V29], 6) Gmat prep: [540 Q39 V26],
7) Veritas Cat: [620 Q46 V30], 8) Veritas Cat: [630 Q45 V32]
SVP
Joined: 03 Jun 2019
Posts: 1514
Location: India
Re: The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

24 Aug 2019, 22:13
Bunuel wrote:
The average of the five numbers is 6.8. If one of the numbers is multiplied by 3, the average of the numbers increases to 9.2. Which of the five numbers is multiplied by 3?

(A) 1.5
(B) 3.0
(C) 3.9
(D) 4.0
(E) 6.0

Kudos for a correct solution.

Given:
1. The average of the five numbers is 6.8.
2. One of the numbers is multiplied by 3, the average of the numbers increases to 9.2.

Asked: Which of the five numbers is multiplied by 3?

Total of 5 numbers = 6.8*5 = 34
Let the number multiplied by 3 be x
34 + 2x = 9.2*5 = 46
x =6

IMO E
_________________
"Success is not final; failure is not fatal: It is the courage to continue that counts."

Please provide kudos if you like my post. Kudos encourage active discussions.

My GMAT Resources: -

Efficient Learning
All you need to know about GMAT quant

Tele: +91-11-40396815
Mobile : +91-9910661622
E-mail : kinshook.chaturvedi@gmail.com
Senior Manager
Joined: 19 Nov 2017
Posts: 254
Location: India
Schools: ISB
GMAT 1: 670 Q49 V32
GPA: 4
Re: The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

24 Aug 2019, 23:33
Let Z be the sum of the four number that is not multiplied by 3
Let Y be the number that is multiplied by 3

Z + Y = 5*6.8 = 34.....(1)
Z + 3Y = 5*9.2 = 46...(2)

Subtract (1) from (2)

2Y = 12
Y = 6

Hence, E.
_________________

Vaibhav

Sky is the limit. 800 is the limit.

~GMAC
GMAT Club Legend
Joined: 18 Aug 2017
Posts: 4738
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
Re: The average of the five numbers is 6.8. If one of the numbers is multi  [#permalink]

### Show Tags

25 Aug 2019, 11:05
Bunuel wrote:
The average of the five numbers is 6.8. If one of the numbers is multiplied by 3, the average of the numbers increases to 9.2. Which of the five numbers is multiplied by 3?

(A) 1.5
(B) 3.0
(C) 3.9
(D) 4.0
(E) 6.0

Kudos for a correct solution.

sum of 5 nos; 34
3x+sum of 4 no ; 46
subtract ; 2x=12 ; x=6
IMOE
_________________
If you liked my solution then please give Kudos. Kudos encourage active discussions.
Re: The average of the five numbers is 6.8. If one of the numbers is multi   [#permalink] 25 Aug 2019, 11:05
Display posts from previous: Sort by