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

 It is currently 22 Oct 2019, 13:10

### 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 seven numbers is 3. Out of these numbers, the average

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 58427
The average of seven numbers is 3. Out of these numbers, the average  [#permalink]

### Show Tags

28 Jan 2019, 04:15
1
1
00:00

Difficulty:

25% (medium)

Question Stats:

77% (01:46) correct 23% (02:13) wrong based on 39 sessions

### HideShow timer Statistics

The average of seven numbers is 3. Out of these numbers, the average of first four numbers is 4 and the average of last four numbers is 4. Then, what is the fourth number?

A. 10

B. 11

C. 12

D. 13

E. 15

_________________
Director
Joined: 09 Mar 2018
Posts: 994
Location: India
The average of seven numbers is 3. Out of these numbers, the average  [#permalink]

### Show Tags

Updated on: 29 Jan 2019, 08:05
Bunuel wrote:
The average of seven numbers is 3. Out of these numbers, the average of first four numbers is 4 and the average of last four numbers is 4. Then, what is the fourth number?

A. 10

B. 11

C. 12

D. 13

E. 15

IMO B

Let a b c d e f & g be the 7 numbers

a+b+c+d+e+f+g = 21
[a+b+c+e+f+g]= 21 - d

a+b+c+d = 16 & d+e+f+g = 16

a+b+c+2d+e+f+g = 32

2d = 32 - [a+b+c+e+f+g]

2d = 32 - 21 +d
d = 11

_________________
If you notice any discrepancy in my reasoning, please let me know. Lets improve together.

Quote which i can relate to.
Many of life's failures happen with people who do not realize how close they were to success when they gave up.

Originally posted by KanishkM on 28 Jan 2019, 04:29.
Last edited by KanishkM on 29 Jan 2019, 08:05, edited 1 time in total.
VP
Joined: 31 Oct 2013
Posts: 1465
Concentration: Accounting, Finance
GPA: 3.68
WE: Analyst (Accounting)
Re: The average of seven numbers is 3. Out of these numbers, the average  [#permalink]

### Show Tags

28 Jan 2019, 04:37
Bunuel wrote:
The average of seven numbers is 3. Out of these numbers, the average of first four numbers is 4 and the average of last four numbers is 4. Then, what is the fourth number?

A. 10

B. 11

C. 12

D. 13

E. 15

Sum of 7 numbers = 7*3 = 21

Sum of first 4 = 4*4 = 16

Sum of last 4 = 4*4 = 16.

NOTE: 4th number has been added 2 times. Therefore :

16 + 16 - 21

32 - 21 = 11.

.
GMAT Club Legend
Joined: 18 Aug 2017
Posts: 5032
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
Re: The average of seven numbers is 3. Out of these numbers, the average  [#permalink]

### Show Tags

28 Jan 2019, 06:22
Bunuel wrote:
The average of seven numbers is 3. Out of these numbers, the average of first four numbers is 4 and the average of last four numbers is 4. Then, what is the fourth number?

A. 10

B. 11

C. 12

D. 13

E. 15

sum of 1st four = 16
last four = 16
and total = 21
so middle no 16+16-21 = 11
IMO B
Re: The average of seven numbers is 3. Out of these numbers, the average   [#permalink] 28 Jan 2019, 06:22
Display posts from previous: Sort by