Last visit was: 24 Apr 2026, 00:17 It is currently 24 Apr 2026, 00:17
Home
Messages
Tests
Schools
Events
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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 23 Apr 2026
Posts: 109,802
Own Kudos:
810,906
Given Kudos: 105,868
Products:
GMAT Club Tests Forum Quiz
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,802
Kudos: 810,906
The average of 10 numbers is 7. What will be the new average if each 12 Aug 2021, 05:30
Kudos
Add Kudos
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

5% (low)

Question Stats:

98% (00:49) correct 2% (02:50) wrong based on 42 sessions

History

Date
Time
Result
Not Attempted Yet
The average of 10 numbers is 7. What will be the new average if each of the numbers is multiplied by 8?

(A) 15
(B) 45
(C) 52
(D) 55
(E) 56
ShowHide Answer
Official Answer
E
avatar
abuc0112
avatar
Joined: 18 Jun 2010
Last visit: 01 Sep 2022
Posts: 82
Own Kudos:
90
Given Kudos: 28
Posts: 82
Kudos: 90
The average of 10 numbers is 7. What will be the new average if each 12 Aug 2021, 05:48
Kudos
Add Kudos
Bookmarks
Bookmark this Post
My attempt:

since each number is multiplied by 8, the old avg will also be multiplied by 8 to get the new avg of 8*7 = 56

Ans:E
User avatar
ash124
User avatar
Joined: 21 Jan 2018
Last visit: 06 Apr 2025
Posts: 107
Own Kudos:
88
Given Kudos: 64
Status:Improving everyday
Location: India
Schools: ISB '23 Judge '23 Said '23 Sloan '24 Fuqua '24 LBS '24 CEIBS '24 INSEAD Jan 22 intake Yale '24
GMAT 1: 660 Q49 V31
GPA: 3.23
WE:Engineering (Aerospace and Defense)
Products:
My Reviews
Schools: ISB '23 Judge '23 Said '23 Sloan '24 Fuqua '24 LBS '24 CEIBS '24 INSEAD Jan 22 intake Yale '24
GMAT 1: 660 Q49 V31
Posts: 107
Kudos: 88
The average of 10 numbers is 7. What will be the new average if each 12 Aug 2021, 06:10
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Understand the question and make inferences:
The average of 10 numbers is 7.
Means total = 10*7 =70

What will be the new average if each of the numbers is multiplied by 8?
If each number is multiplied by 8 then the total will be multiplied by 8
= 70 * 8
As we need to take the average out
the sum of numbers/no. of numbers
= 70*8/10
= 56
Answer : E
User avatar
QuantMadeEasy
User avatar
Joined: 28 Feb 2014
Last visit: 01 Mar 2026
Posts: 502
Own Kudos:
802
Given Kudos: 78
Location: India
Concentration: General Management, International Business
GPA: 3.97
WE:Engineering (Education)
Posts: 502
Kudos: 802
The average of 10 numbers is 7. What will be the new average if each 12 Aug 2021, 06:35
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Quote:
The average of 10 numbers is 7. What will be the new average if each of the numbers is multiplied by 8?
Show more

Step 1: Calculation
If each number is multiplied by 8, then old average is also multiplied by 8 to get new average.
New average = 56

E is correct

PS: This is applicable to adding, subtracting or multiplying a constant to each number.
User avatar
BrushMyQuant
User avatar
Joined: 05 Apr 2011
Last visit: 03 Apr 2026
Posts: 2,286
Own Kudos:
2,680
Given Kudos: 100
Status:Tutor - BrushMyQuant
Location: India
Concentration: Finance, Marketing
Schools: XLRI (A)
GMAT 1: 700 Q51 V31
GPA: 3
WE:Information Technology (Computer Software)
Expert
Expert reply
Schools: XLRI (A)
GMAT 1: 700 Q51 V31
Posts: 2,286
Kudos: 2,680
The average of 10 numbers is 7. What will be the new average if each 03 Aug 2022, 20:50
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Theory

    ➡ Average or Arithmetic Mean = Sum of all the Values / Total Number of Values
    ➡ Sum of All the values = Average * Total Number of Values
    ➡ If all the numbers in the set are multiplied/divided by the same number(k) then the mean also gets multiplied/divided by the same number(k)

The average of 10 numbers is 7. What will be the new average if each of the numbers is multiplied by 8

Using the theory, even the average will get multiplied by 8
=> New Average = Old Average * 8 = 7 * 8 = 56

So, Answer will be E.

Explaining in bit more detail below:

The average of 10 numbers is 7

Sum = Average * 10 = 7*10 = 70

The new average if each of the numbers is multiplied by 8

New Sum = Old Sum * 8 (As all numbers are multiplied by 8, so overall sum will also get multiplied by 8)
=> New Sum = 70*8 = 560

New Average = \(\frac{Sum}{10}\) = \(\frac{560}{10}\) = 56

So, Answer will be E.
Hope it helps!

Watch the following video to Learn the Basics of Statistics

Moderators:
Bunuel
Math Expert
109802 posts
Krunaal
Tuck School Moderator
853 posts