|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
06 Feb 2026, 05:01
Kudos
Bookmarks
A
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:
65% (02:03) correct
35%
(02:11)
wrong
based on 120
sessions
History
Date
Time
Result
Not Attempted Yet
A teacher corrected the first half of a stack of exams at a rate of 9 exams per hour and the second half of the stack at a rate of 18 exams per hour. If it took her 4 hours to correct all of the exams, how many exams were in the stack?
A. 48
B. 50
C. 52
D. 54
E. 56
A. 48
B. 50
C. 52
D. 54
E. 56
06 Feb 2026, 06:05
Kudos
Bookmarks
So first half is marked at 9 eph (exams per hour) second half at 18 eph.
Since the rate doubles from 9 -> 18, the time taken to complete the same of work is halved. (we know the work is the same amount as they each perform 1/2).
So when working at 18 eph is takes 1T of time to complete half, and when working at 9 eph it takes 2T to complete a half. So total time takes 3T
work done = rate x time
This means the total work done (D) = 18T + 9(2T)
4 hours total divided by 3T means T=4/3 hours
18(4/3) + 9 x 2 x(4/3) = 48
Since the rate doubles from 9 -> 18, the time taken to complete the same of work is halved. (we know the work is the same amount as they each perform 1/2).
So when working at 18 eph is takes 1T of time to complete half, and when working at 9 eph it takes 2T to complete a half. So total time takes 3T
work done = rate x time
This means the total work done (D) = 18T + 9(2T)
4 hours total divided by 3T means T=4/3 hours
18(4/3) + 9 x 2 x(4/3) = 48
poojaarora1818
Joined: 30 Jul 2019
Last visit: 29 Apr 2026
Posts: 1,631
Given Kudos: 3,825
Location: India
Concentration: General Management, Economics
Schools: Duke '27 Haas '27 Kelley '27 Kellogg '27 McDonough '27
GPA: 3
WE:Human Resources (Real Estate)
Products:
06 Feb 2026, 08:36
Kudos
Bookmarks
By applying the matrix approach, we can get an answer
As we know
\(\frac{E}{9} \)+ \(\frac{E}{18} \)= 4(total time mentioned in the question)
E= 24
Total Exams = 24 +24 = 48
Answer: A
| Rate | Time | Exam | |
| First half | 9 | E/9 | E |
| Second half | 18 | E/18 | E |
As we know
\(\frac{E}{9} \)+ \(\frac{E}{18} \)= 4(total time mentioned in the question)
E= 24
Total Exams = 24 +24 = 48
Answer: A
kevincan
