Last visit was: 02 Sep 2026, 22:39 It is currently 02 Sep 2026, 22:39
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.
Close
Request Expert Reply
Confirm Cancel
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 02 Sep 2026
Posts: 113,072
Own Kudos:
838,737
 [2]
Given Kudos: 111,295
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 113,072
Kudos: 838,737
 [2]
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
User avatar
GMATinsight
User avatar
Major Poster
Joined: 08 Jul 2010
Last visit: 31 Aug 2026
Posts: 7,290
Own Kudos:
Given Kudos: 128
Status:GMAT/GRE Tutor l Admission Consultant l On-Demand Course creator
Location: India
GMAT: QUANT+DI EXPERT
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
WE:Education (Education)
Products:
Expert
Expert reply
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
Posts: 7,290
Kudos: 17,475
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
xyz12345678
Joined: 12 Apr 2025
Last visit: 07 Dec 2025
Posts: 25
Own Kudos:
6
 [1]
Given Kudos: 20
Posts: 25
Kudos: 6
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
sanjitscorps18
Joined: 26 Jan 2019
Last visit: 03 Mar 2026
Posts: 723
Own Kudos:
757
 [1]
Given Kudos: 130
Location: India
Schools: IMD'26
Products:
Schools: IMD'26
Posts: 723
Kudos: 757
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
John and Jack are among 10 students who write an examination. John scored 80 marks. The average score of the 8 students other than them is 72.5

Jack + John + (8 other student scores) = Avg * 10
Jack + 80 + 72.5 * 8 = Avg * 10
Jack + 80 + 580 = Avg * 10
Jack + 660 = Avg * 10
(Jack + 660)/10 = Avg ========== (a)

The average score of all the 10 students is one more than the average score of the 9 students other than John.

Avg = Avg(9) + 1
Avg = 1 + (Jack + 72.5 * 8)/9
Avg = (Jack + 580 + 9)/9 ========== (b)

Now considering (a) and (b)
(Jack + 580 - 9)/9 = (Jack + 660)/10
10 Jack + 589 * 10 = 9 Jack + 660 * 9
Jack = 660 * 9 - 589 * 10

The score of Jack is
Jack = 50

Option C
User avatar
RDM42
Joined: 20 Jan 2025
Last visit: 24 Aug 2026
Posts: 464
Own Kudos:
328
 [1]
Given Kudos: 29
Posts: 464
Kudos: 328
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
John= 80 marks
(The average score of the 8 students other than them is 72.5)
(Sum of 8 students score/8) = 72.5
Sum of 8 students score = 72.5*8= 580 marks

The average score of all the 10 students is one more than the average score of the 9 students other than John.

Average score of 10 students= Average score of 9 students +1
((John+Jack+ Sum(8))/10) = ((Jack+ Sum(8))/9) +1
(80+Jack+580)/10 = (Jack+580+9)/9
(Jack+660)9= 10(Jack+589)
9 Jack+ 5,940 = 10 Jack + 5890
Jack= 5940-5890= 50

Answer: C
avatar
ManifestDreamMBA
Joined: 17 Sep 2024
Last visit: 01 Jul 2026
Posts: 1,382
Own Kudos:
928
 [1]
Given Kudos: 243
Posts: 1,382
Kudos: 928
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Let scores of John be x and Jack be y
x = 80
Avg of 8 students = 72.5
Total score of 8 students = 72.5*8 =580

(580+y)/9 + 1= (580+80+y)/10
(589+y)*10 = (660+y)*9
y = 50
Bunuel
John and Jack are among 10 students who write an examination. John scored 80 marks. The average score of the 8 students other than them is 72.5. The average score of all the 10 students is one more than the average score of the 9 students other than John. The score of Jack is

A. 40
B. 45
C. 50
D. 55
E. 60


­
User avatar
HarshavardhanR
Joined: 16 Mar 2023
Last visit: 02 Sep 2026
Posts: 649
Own Kudos:
Given Kudos: 99
Status:Independent GMAT Tutor
Affiliations: Ex - Director, Subject Matter Expertise at e-GMAT
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 649
Kudos: 755
Kudos
Add Kudos
Bookmarks
Bookmark this Post


Harsha
Attachment:
GMAT-Club-Forum-tup3dtz0.png
GMAT-Club-Forum-tup3dtz0.png [ 157.11 KiB | Viewed 1115 times ]
Moderator:
Math Expert
113072 posts