Last visit was: 16 Jul 2025, 00:38 It is currently 16 Jul 2025, 00:38
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: 16 July 2025
Posts: 102,585
Own Kudos:
741,756
 [5]
Given Kudos: 98,191
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 102,585
Kudos: 741,756
 [5]
1
Kudos
Add Kudos
3
Bookmarks
Bookmark this Post
User avatar
0akshay0
Joined: 19 Apr 2016
Last visit: 14 Jul 2019
Posts: 194
Own Kudos:
Given Kudos: 59
Location: India
GMAT 1: 570 Q48 V22
GMAT 2: 640 Q49 V28
GPA: 3.5
WE:Web Development (Computer Software)
GMAT 2: 640 Q49 V28
Posts: 194
Kudos: 622
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
ScottTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 14 Oct 2015
Last visit: 15 Jul 2025
Posts: 21,119
Own Kudos:
26,170
 [4]
Given Kudos: 296
Status:Founder & CEO
Affiliations: Target Test Prep
Location: United States (CA)
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 21,119
Kudos: 26,170
 [4]
3
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
User avatar
Abhishek009
User avatar
Board of Directors
Joined: 11 Jun 2011
Last visit: 21 Apr 2025
Posts: 5,965
Own Kudos:
5,159
 [1]
Given Kudos: 463
Status:QA & VA Forum Moderator
Location: India
GPA: 3.5
WE:Business Development (Commercial Banking)
Posts: 5,965
Kudos: 5,159
 [1]
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
Bunuel
A mathematics professor can grade 20 exam papers in one day. How long will it take him to grade 30 papers if he is joined a colleague grading twice as fast?

A. 1/2 day
B. 3/4 day
C. 1 day
D. 3/2 days
E. 2 days

Efficiency of 1st professor = 20 papers/day
Efficiency of 2nd professor = 40 papers/day

Combined efficiency of 1st & 2nd Professor is 60 papers/day

Quote:
How long will it take him to grade 30 papers

Time taken by the 2 professors to grade 30 papers is \(\frac{30}{60}\) = \(\frac{1}{2}\) days..

Thus, the correct , answer must be (A) \(\frac{1}{2}\) days...
User avatar
mbaprep2016
Joined: 29 May 2016
Last visit: 30 Jun 2018
Posts: 72
Own Kudos:
Given Kudos: 362
Posts: 72
Kudos: 94
Kudos
Add Kudos
Bookmarks
Bookmark this Post
individually they have 20 and 40 papers in a days
together they can have 60 papers in 1 days ... do for 30 it required 1/2 day ...
A is the answer
User avatar
RohitSaluja
Joined: 02 Aug 2020
Last visit: 21 Sep 2024
Posts: 214
Own Kudos:
90
 [1]
Given Kudos: 254
Location: India
Concentration: General Management, Healthcare
Schools: HEC'22 (J)
GMAT 1: 720 Q49 V40
GPA: 3.8
WE:Consulting (Healthcare/Pharmaceuticals)
Products:
Schools: HEC'22 (J)
GMAT 1: 720 Q49 V40
Posts: 214
Kudos: 90
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
In the problem it is mentioned that he can grade 20 papers in a day. So rate at which work is done by this professor is 20 paper per day.
He is joined by a professor who is twice as fast as him, so his rate would be 40 paper per day.

Combined they can grade 20 + 40 = 60 paper per day. So 30 papers could be graded in 30/60 days = 1/2 day
User avatar
MathRevolution
User avatar
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Last visit: 27 Sep 2022
Posts: 10,078
Own Kudos:
Given Kudos: 4
GMAT 1: 760 Q51 V42
GPA: 3.82
Expert
Expert reply
GMAT 1: 760 Q51 V42
Posts: 10,078
Kudos: 18,747
Kudos
Add Kudos
Bookmarks
Bookmark this Post
A mathematics professor can grade 20 exam papers in one day.

His colleague grading twice as fast: 40 exam papers in one day

Working together: 20 + 40 = 60 papers one day.

Work required to be done: 30 papers.

Time required: \(\frac{1}{2}\) day.

Answer A
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 37,413
Own Kudos:
Posts: 37,413
Kudos: 1,013
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Moderators:
Math Expert
102585 posts
PS Forum Moderator
695 posts