Last visit was: 23 Apr 2026, 20:42 It is currently 23 Apr 2026, 20:42
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: 109,785
Own Kudos:
810,878
 [4]
Given Kudos: 105,853
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: 109,785
Kudos: 810,878
 [4]
If x = 80%, by what percent is x larger than x^2? Updated on: 08 Mar 2026, 04:27
Originally posted by Bunuel on 12 Mar 2023, 06:08.
Last edited by Bunuel on 08 Mar 2026, 04:27, edited 1 time in total.
Kudos
Add Kudos
4
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

45% (medium)

Question Stats:

61% (01:11) correct 39% (01:19) wrong based on 169 sessions

History

Date
Time
Result
Not Attempted Yet
If x = 80%, by what percent is x larger than x^2?

(A) 8%
(B) 16%
(C) 20%
(D) 25%
(E) 80%
ShowHide Answer
Official Answer
D
User avatar
stne
User avatar
Joined: 27 May 2012
Last visit: 23 Apr 2026
Posts: 1,809
Own Kudos:
2,090
 [3]
Given Kudos: 679
Posts: 1,809
Kudos: 2,090
 [3]
If x = 80%, by what percent is x larger than x^2? 14 Mar 2023, 10:57
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
If x = 80%, by what percent is x larger than x^2?


(A) 8 %
(B) 16 %
(C) 20 %
(D) 25%
(E) 80%
Show more

\(x= \frac{80}{100} = \frac{4}{5} \)...(i)

\(x^2= \frac{16}{25} \)...(ii)

Required \(\% = (\frac{i - ii}{ii}) *100= 25\%\)

Ans =D

Hope it helps.
User avatar
tamsinlct
User avatar
Joined: 07 Feb 2026
Last visit: 23 Apr 2026
Posts: 1
Given Kudos: 10
Products:
Forum Quiz
Posts: 1
Kudos: 0
If x = 80%, by what percent is x larger than x^2? 08 Mar 2026, 03:46
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hi,

Can you help walk me through your choice of (i) and (ii) for old and new in percentage change formula?

If we were to put x = Old and x^2 = New, then we have the following:

= (x^2 - x)/x
= ((80/100)^2 - (80/100)) / (80/100)
= (80/100) - 1
= -20%

So x is 20% larger than x^2


However, if we were to put x^2= new, and x = old, then we have the following:

= (x - x^2)/ x^2
= ((80/100) - (80/100)^2) /(80/100)^2
= (20/100)*(100/80)
=1/4 = 25%

So x is 25% larger than x^2

Or am I missing something/making a mistake somewhere?

stne


\(x= \frac{80}{100} = \frac{4}{5} \)...(i)

\(x^2= \frac{16}{25} \)...(ii)

Required \(\% = (\frac{i - ii}{ii}) *100= 25\%\)

Ans =D

Hope it helps.
Show more
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 23 Apr 2026
Posts: 109,785
Own Kudos:
810,878
 [1]
Given Kudos: 105,853
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: 109,785
Kudos: 810,878
 [1]
If x = 80%, by what percent is x larger than x^2? 08 Mar 2026, 04:45
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
If x = 80%, by what percent is x larger than x^2?

(A) 8%
(B) 16%
(C) 20%
(D) 25%
(E) 80%

x = 80% = 0.8
x^2 = 0.8 * 0.8 = 0.64

Percent by which x is larger than x^2:

(x - x^2)/x^2 * 100 =
= (0.8 - 0.64)/0.64 * 100 =
= 0.25 * 100 =
= 25%

Answer: D.


tamsinlct
Hi,

Can you help walk me through your choice of (i) and (ii) for old and new in percentage change formula?

If we were to put x = Old and x^2 = New, then we have the following:

= (x^2 - x)/x
= ((80/100)^2 - (80/100)) / (80/100)
= (80/100) - 1
= -20%

So x is 20% larger than x^2


However, if we were to put x^2= new, and x = old, then we have the following:

= (x - x^2)/ x^2
= ((80/100) - (80/100)^2) /(80/100)^2
= (20/100)*(100/80)
=1/4 = 25%

So x is 25% larger than x^2

Or am I missing something/making a mistake somewhere?


Show more

The general formula for calculating percent increase or decrease (percent change) is: \(\frac{\text{Difference in values}}{\text{Reference value}}*100\). The reference value is the value you are comparing to. This means the reference value always goes in the denominator of the formula.

(When we are talking about percentage change from old value to new value, it would be \(\frac{\text{New Value - Old Value }}{\text{Old Value}}*100\).­)

In this question, we are comparing to x^2 (If x = 80%, by what percent is x larger than x^2?), so the reference value is x^2, which means it must go in the denominator.

Hope it's clear.­
User avatar
Adit_
User avatar
Joined: 04 Jun 2024
Last visit: 23 Apr 2026
Posts: 694
Own Kudos:
227
Given Kudos: 116
Posts: 694
Kudos: 227
If x = 80%, by what percent is x larger than x^2? 08 Mar 2026, 04:48
Kudos
Add Kudos
Bookmarks
Bookmark this Post
80% = 4/5
squaring it will give 16/25 and to see by how much percent 4/5 is greater its simply

16/25*x = 4/5

x=5/4
Or it is greater by 25%
Bunuel
If x = 80%, by what percent is x larger than x^2?

(A) 8%
(B) 16%
(C) 20%
(D) 25%
(E) 80%
Show more
Moderators:
Bunuel
Math Expert
109785 posts
Krunaal
Tuck School Moderator
853 posts