Last visit was: 17 Jul 2024, 05:19 It is currently 17 Jul 2024, 05:19
Toolkit
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
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

# The average (arithmetic mean) of five numbers is 3x + 4. If one of the

SORT BY:
Tags:
Show Tags
Hide Tags
Math Expert
Joined: 02 Sep 2009
Posts: 94371
Own Kudos [?]: 641614 [7]
Given Kudos: 85627
Manager
Joined: 10 Sep 2014
Posts: 58
Own Kudos [?]: 268 [1]
Given Kudos: 102
Math Expert
Joined: 02 Sep 2009
Posts: 94371
Own Kudos [?]: 641614 [0]
Given Kudos: 85627
Intern
Joined: 29 Oct 2014
Posts: 31
Own Kudos [?]: 20 [0]
Given Kudos: 194
Re: The average (arithmetic mean) of five numbers is 3x + 4. If one of the [#permalink]
TARGET730 wrote:
The answer is 2x + 6, which is not given in the answer choices

im getting (2x+4)
Manager
Joined: 25 Feb 2010
Posts: 208
Own Kudos [?]: 322 [2]
Given Kudos: 10
Re: The average (arithmetic mean) of five numbers is 3x + 4. If one of the [#permalink]
1
Kudos
7x-4 + y (all four numbers) / 5 = 3x+4

7x-4 +y = 15x+20

y = 8x+24

Avg. of 4 numbers = 2x+6.
Manager
Joined: 18 Dec 2014
Posts: 95
Own Kudos [?]: 49 [0]
Given Kudos: 5
Re: The average (arithmetic mean) of five numbers is 3x + 4. If one of the [#permalink]
This is what I did;

5 numbers, average of 5 numbers = 3x+4
5*(3x+4) = 15x + 20
15x + 20 - 7x - 4= 8x + 16

8x + 16 / 4 = 2x + 4.

What did I do wrong?
Manager
Joined: 13 Jun 2012
Posts: 166
Own Kudos [?]: 508 [0]
Given Kudos: 467
Location: United States
WE:Supply Chain Management (Computer Hardware)
Re: The average (arithmetic mean) of five numbers is 3x + 4. If one of the [#permalink]
SavageBrother wrote:
This is what I did;

5 numbers, average of 5 numbers = 3x+4
5*(3x+4) = 15x + 20
15x + 20 - 7x - 4= 8x + 16

8x + 16 / 4 = 2x + 4.

What did I do wrong?

You forgot the minus buddy! 15x + 20 - (7x - 4)= 8x + 24 / 4 is the answer!
SVP
Joined: 27 Dec 2012
Status:The Best Or Nothing
Posts: 1558
Own Kudos [?]: 7294 [0]
Given Kudos: 193
Location: India
Concentration: General Management, Technology
WE:Information Technology (Computer Software)
Re: The average (arithmetic mean) of five numbers is 3x + 4. If one of the [#permalink]
Answer = D. 2x + 6

Let the addition of other 4 numbers = a; we require to find $$\frac{a}{4}$$

$$\frac{a + 7x-4}{5} = 3x+4$$

a = 8x+24

$$\frac{a}{4} = 2x+6$$
Intern
Joined: 22 Aug 2014
Posts: 30
Own Kudos [?]: 37 [1]
Given Kudos: 6
Re: The average (arithmetic mean) of five numbers is 3x + 4. If one of the [#permalink]
1
Kudos
Bunuel wrote:
The average (arithmetic mean) of five numbers is 3x + 4. If one of the numbers is 7x - 4, what is the average of the other four numbers?

A. 1.6x + 3.2
B. 1.6x + 4.8
C. 2x + 4
D. 2x + 6
E. 4x + 8

Kudos for a correct solution.

Sum(5 nos)/5 = 3x + 4
Sum(7x-4 + 4 nos) = 15x + 20
Sum( 4 nos) = 8x + 24
AM(4 nos) = 2x + 6

Option D
Intern
Joined: 22 Aug 2014
Posts: 30
Own Kudos [?]: 37 [1]
Given Kudos: 6
Re: The average (arithmetic mean) of five numbers is 3x + 4. If one of the [#permalink]
1
Kudos
Bunuel wrote:
The average (arithmetic mean) of five numbers is 3x + 4. If one of the numbers is 7x - 4, what is the average of the other four numbers?

A. 1.6x + 3.2
B. 1.6x + 4.8
C. 2x + 4
D. 2x + 6
E. 4x + 8

Kudos for a correct solution.

Sum(5 nos)/5 = 3x + 4
Sum(7x-4 + 4 nos) = 15x + 20
Sum( 4 nos) = 8x + 24
AM(4 nos) = 2x + 6

Option D
Math Expert
Joined: 02 Sep 2009
Posts: 94371
Own Kudos [?]: 641614 [1]
Given Kudos: 85627
Re: The average (arithmetic mean) of five numbers is 3x + 4. If one of the [#permalink]
1
Kudos
Bunuel wrote:
The average (arithmetic mean) of five numbers is 3x + 4. If one of the numbers is 7x - 4, what is the average of the other four numbers?

A. 1.6x + 3.2
B. 1.6x + 4.8
C. 2x + 4
D. 2x + 6
E. 4x + 8

Kudos for a correct solution.

MAGOOSH OFFICIAL SOLUTION:
Attachment:

averageis3xplus4_text.PNG [ 18.42 KiB | Viewed 9520 times ]
Alum
Joined: 12 Aug 2015
Posts: 2271
Own Kudos [?]: 3196 [0]
Given Kudos: 893
GRE 1: Q169 V154
Re: The average (arithmetic mean) of five numbers is 3x + 4. If one of the [#permalink]
Here is my solution to this one -->
Sum(5)=> 15x+20
Sum(4)=> 15x+20-(7x-4) => 8x+24
Hence Mean of 4 numbers -> 2x+6

Hence D
e-GMAT Representative
Joined: 04 Jan 2015
Posts: 3712
Own Kudos [?]: 17324 [0]
Given Kudos: 165
Re: The average (arithmetic mean) of five numbers is 3x + 4. If one of the [#permalink]

Solution

Given
• The average (arithmetic mean) of five numbers is 3x + 4
• one of the numbers is 7x – 4.

To find
• The average of the other four numbers.

Approach and Working out

• Average of 5 numbers = 3x +4
o Sum of numbers / 5 = 3x+4
• One of the numbers = 7x-4
o 7x -4 + sum of remaining 4 numbers / 5 = 3x + 4
o 7x -4 + sum of remaining 4 numbers = 15x + 20
o Sum of remaining 4 numbers = 8x + 24
• Average of remaining 4 numbers = 8x +24 /4 = 2x +6
Thus, option D is the correct answer.
Intern
Joined: 02 Nov 2019
Posts: 9
Own Kudos [?]: 2 [0]
Given Kudos: 10
The average (arithmetic mean) of five numbers is 3x + 4. If one of the [#permalink]
The total of the five numbers is $$5*(3x+4)=15x+20$$
One of the numbers is $$7x-4$$. Therefore, $$15x+20=(7x-4)+a+b+c+d$$
and $$8x+24=a+b+c+d$$
So the average of the other four numbers (a, b, c, d) is $$\frac{(8x+24)}{4}=2x+6$$ (Answer D)
Target Test Prep Representative
Joined: 14 Oct 2015
Status:Founder & CEO
Affiliations: Target Test Prep
Posts: 19148
Own Kudos [?]: 22654 [0]
Given Kudos: 286
Location: United States (CA)
Re: The average (arithmetic mean) of five numbers is 3x + 4. If one of the [#permalink]
Bunuel wrote:
The average (arithmetic mean) of five numbers is 3x + 4. If one of the numbers is 7x - 4, what is the average of the other four numbers?

A. 1.6x + 3.2
B. 1.6x + 4.8
C. 2x + 4
D. 2x + 6
E. 4x + 8

Kudos for a correct solution.

Remember that average = sum / quantity. Since the average of the five numbers is 3x + 4, the sum of these five numbers is 5 * (3x + 4) = 15x + 20. We are told that one of the numbers is 7x - 4, thus the sum of the remaining four numbers is 15x + 20 - (7x - 4) = 15x + 20 - 7x + 4 = 8x + 24. Since the sum of the four numbers besides 7x - 4 is 8x + 24, the average of these four numbers is (8x + 24)/4 = 8x/4 + 24/4 = 2x + 6.