Last visit was: 04 Sep 2026, 14:22 It is currently 04 Sep 2026, 14:22
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
KSBGC
User avatar
Joined: 31 Oct 2013
Last visit: 10 Mar 2022
Posts: 1,239
Own Kudos:
1,551
 [44]
Given Kudos: 635
Concentration: Accounting, Finance
GPA: 3.68
WE:Analyst (Accounting)
Posts: 1,239
Kudos: 1,551
 [44]
In an exam 62% of the students were declared as passed. However, due t Updated on: 28 Jan 2018, 06:25
Originally posted by KSBGC on 28 Jan 2018, 04:53.
Last edited by chetan2u on 28 Jan 2018, 06:25, edited 1 time in total.
Renamed the topic
3
Kudos
Add Kudos
39
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

75% (hard)

Question Stats:

61% (02:43) correct 39% (02:57) wrong based on 337 sessions

History

Date
Time
Result
Not Attempted Yet
In an exam 62% of the students were declared as passed. However, due to complication error, 20% of the students who have actually passed were shown as failed and 20% of the students who have actually failed were declared as passed. what % of the students actually passed?

a) 68
b) 70
c) 72
d) 75
e) 75.5
ShowHide Answer
Official Answer
B
Most Helpful Reply
User avatar
chetan2u
User avatar
GMAT Expert
Joined: 02 Aug 2009
Last visit: 04 Sep 2026
Posts: 11,288
Own Kudos:
46,086
 [8]
Given Kudos: 339
Status:Math and DI Expert
Location: India
Concentration: Human Resources, General Management
GMAT Focus 1: 735 Q90 V89 DI81
Products:
My Reviews
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
GMAT Focus 1: 735 Q90 V89 DI81
Posts: 11,288
Kudos: 46,086
 [8]
In an exam 62% of the students were declared as passed. However, due t 22 Mar 2020, 00:37
6
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
DazednConfused
chetan2u
selim
In an exam 62% of the students were declared as passed. However, due to complication error, 20% of the students who have actually passed were shown as failed and 20% of the students who have actually failed were declared as passed. what % of the students actually passed?

a) 68
b) 70
c) 72
d) 75
e) 75.5

Let there be p passed in 100 students, so 100-p failed..
So 62 consists of 80%pass and 20% fail..
0.8p+0.2(100-p)=62......0.8p+20-0.2p=62..
0.6p=42.....p=70

B

chetan2u I don't know if you will see this after so long but can you please explain why you did "62% consists of 80% passed & 20% failed"? That part completely went over my head...
Show more

Hi,

Overall 62% have been declared pass...
say total is T..
Thus 0.62T are declared passed

This, 0.62T consists of two groups.
1) Actual passed- 20% of these were erroneously declared FAIL.. So 80% are part of the declared passed, that is 62% of total. If P actually passed, then 0.80 are part of 0.62T
2) Actual failed- 20% of these were erroneously declared PASS.. So 20% are part of the declared passed, that is 62% of total. If P% actually passed, then (100-p)% actually failed. 20% of (100-P)%=0.20(100-P), who are part of 0.62T

Let us take T as 100..
Thus \(0.8p+0.2(100-p)=62\)......
\(0.8p+20-0.2p=62\)..
\(0.6p=42.....p=70\)
User avatar
KarishmaB
User avatar
Joined: 16 Oct 2010
Last visit: 03 Sep 2026
Posts: 16,638
Own Kudos:
81,171
 [6]
Given Kudos: 489
Location: Pune, India
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 16,638
Kudos: 81,171
 [6]
In an exam 62% of the students were declared as passed. However, due t 22 Mar 2020, 02:38
6
Kudos
Add Kudos
Bookmarks
Bookmark this Post
KSBGC
In an exam 62% of the students were declared as passed. However, due to complication error, 20% of the students who have actually passed were shown as failed and 20% of the students who have actually failed were declared as passed. what % of the students actually passed?

a) 68
b) 70
c) 72
d) 75
e) 75.5
Show more


Say there were 100 students. p passed and (100 - p) failed.

62 = (80/100)*p + (20/100)*(100 - p)

42 = 3p/5

p = 70

Answer (B)
General Discussion
User avatar
chetan2u
User avatar
GMAT Expert
Joined: 02 Aug 2009
Last visit: 04 Sep 2026
Posts: 11,288
Own Kudos:
46,086
 [5]
Given Kudos: 339
Status:Math and DI Expert
Location: India
Concentration: Human Resources, General Management
GMAT Focus 1: 735 Q90 V89 DI81
Products:
My Reviews
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
GMAT Focus 1: 735 Q90 V89 DI81
Posts: 11,288
Kudos: 46,086
 [5]
In an exam 62% of the students were declared as passed. However, due t 28 Jan 2018, 06:24
2
Kudos
Add Kudos
3
Bookmarks
Bookmark this Post
selim
In an exam 62% of the students were declared as passed. However, due to complication error, 20% of the students who have actually passed were shown as failed and 20% of the students who have actually failed were declared as passed. what % of the students actually passed?

a) 68
b) 70
c) 72
d) 75
e) 75.5
Show more

Let there be p passed in 100 students, so 100-p failed..
So 62 consists of 80%pass and 20% fail..
0.8p+0.2(100-p)=62......0.8p+20-0.2p=62..
0.6p=42.....p=70

B
avatar
juthi223
avatar
Joined: 02 Aug 2019
Last visit: 20 Nov 2019
Posts: 1
Own Kudos:
1
 [1]
Given Kudos: 5
Posts: 1
Kudos: 1
 [1]
In an exam 62% of the students were declared as passed. However, due t 20 Nov 2019, 11:40
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Whats wrong with.this approach
62*80% +30*20%?

Posted from my mobile device
avatar
DazednConfused
avatar
Joined: 13 Jan 2017
Last visit: 12 Jun 2021
Posts: 7
Own Kudos:
3
 [1]
Given Kudos: 1
Location: India
Concentration: Strategy, Technology
GMAT 1: 780 Q51 V48
GPA: 3.76
GMAT 1: 780 Q51 V48
Posts: 7
Kudos: 3
 [1]
In an exam 62% of the students were declared as passed. However, due t 21 Mar 2020, 11:24
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
chetan2u
selim
In an exam 62% of the students were declared as passed. However, due to complication error, 20% of the students who have actually passed were shown as failed and 20% of the students who have actually failed were declared as passed. what % of the students actually passed?

a) 68
b) 70
c) 72
d) 75
e) 75.5

Let there be p passed in 100 students, so 100-p failed..
So 62 consists of 80%pass and 20% fail..
0.8p+0.2(100-p)=62......0.8p+20-0.2p=62..
0.6p=42.....p=70

B
Show more

chetan2u I don't know if you will see this after so long but can you please explain why you did "62% consists of 80% passed & 20% failed"? That part completely went over my head...
avatar
fireagablast
avatar
Joined: 30 Jun 2019
Last visit: 17 Aug 2021
Posts: 259
Own Kudos:
133
Given Kudos: 8
Posts: 259
Kudos: 133
In an exam 62% of the students were declared as passed. However, due t 24 Mar 2020, 17:36
Kudos
Add Kudos
Bookmarks
Bookmark this Post
As someone else asked above why does this not work:
62*8/10 + 38*2/10

The more i look at it, the more confused i get. How can the % of passed people increase when the portion of false positives is larger than false negatives?

I think the problem is worded incorrectly, or at least portrays the wrong meaning. As written, the problem reads like they are of two separate quantities "Of the 62% marked passed, only 80% passed, and of the 38% marked failed, 20% passed". Which is completely different from how it's being solved here "62% is the mixture of 80% pass and 20% fail" or "Of the 62% that passed, 20% of the passed were removed and 20% failed was added"
User avatar
Mansoor50
User avatar
Joined: 29 May 2017
Last visit: 04 Jul 2021
Posts: 137
Own Kudos:
33
 [1]
Given Kudos: 63
Location: Pakistan
Concentration: Social Entrepreneurship, Sustainability
Posts: 137
Kudos: 33
 [1]
In an exam 62% of the students were declared as passed. However, due t 27 Mar 2020, 04:22
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
VeritasKarishma
does this make sense?

actual passed is x and actual failed is 100-x

0.2x needs to be added to the 62, since 20% of the actual passed had been classified as failed
and
0.2(100-x) need to be taken out of 62 since they had failed but shown as passed.

thus:

0.62 + 0.2x - 0.2(100-x) = x (that is, adding the actual passed and taking out the actul failed, shd give us the actual passed, x)

simplifying we get:

0.62 - 20 = 0.6x

---- this is where the arithmetic fails......that 20 is a problem.....if i turn it into a 0.2, i get 70!

which makes me think if my logic is incrrect.?
User avatar
saif39571
User avatar
Joined: 19 Mar 2024
Last visit: 27 Jul 2026
Posts: 1
Own Kudos:
1
 [1]
Given Kudos: 148
Posts: 1
Kudos: 1
 [1]
In an exam 62% of the students were declared as passed. However, due t 15 Oct 2024, 06:04
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
the answer shouldn't be 70, the error I think is including 80% of passed students in 62, where it should be 100%
so the equation is:
62= p+ 20%(100-p)
p= 52.5%
User avatar
Devil90
User avatar
Joined: 20 Dec 2024
Last visit: 25 Jun 2025
Posts: 2
Own Kudos:
2
 [2]
Given Kudos: 6
Posts: 2
Kudos: 2
 [2]
In an exam 62% of the students were declared as passed. However, due t 20 Dec 2024, 03:30
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
Rule of alligation

80....... 20
..... 62
42........ 18

Actually passed : actually failed = 42:18 = 7:3

In percentage actually passed
= 7/10 * 100
= 70%
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 39,217
Own Kudos:
1,157
Posts: 39,217
Kudos: 1,157
In an exam 62% of the students were declared as passed. However, due t 15 Jun 2026, 15:58
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.
Moderator:
Bunuel
Math Expert
113146 posts