Last visit was: 19 Nov 2025, 09:31 It is currently 19 Nov 2025, 09:31
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: 19 Nov 2025
Posts: 105,389
Own Kudos:
Given Kudos: 99,977
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 105,389
Kudos: 778,287
 [16]
Kudos
Add Kudos
16
Bookmarks
Bookmark this Post
Most Helpful Reply
avatar
srikalivarapu
Joined: 04 Sep 2019
Last visit: 04 Mar 2021
Posts: 25
Own Kudos:
39
 [6]
Given Kudos: 25
Posts: 25
Kudos: 39
 [6]
6
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
chetan2u
User avatar
GMAT Expert
Joined: 02 Aug 2009
Last visit: 15 Nov 2025
Posts: 11,238
Own Kudos:
43,703
 [6]
Given Kudos: 335
Status:Math and DI Expert
Location: India
Concentration: Human Resources, General Management
GMAT Focus 1: 735 Q90 V89 DI81
Products:
Expert
Expert reply
GMAT Focus 1: 735 Q90 V89 DI81
Posts: 11,238
Kudos: 43,703
 [6]
3
Kudos
Add Kudos
3
Bookmarks
Bookmark this Post
General Discussion
avatar
ask1
Joined: 02 Apr 2018
Last visit: 19 Jul 2020
Posts: 40
Own Kudos:
Given Kudos: 24
Location: India
Concentration: Operations, Social Entrepreneurship
Posts: 40
Kudos: 8
Kudos
Add Kudos
Bookmarks
Bookmark this Post
chetan2u

Can you kindly help me with the weighted average calculation here?
How did you go from Correct Total Incorrect statement to the Fraction in the next sentence?

What I didnt understand is why correct and incorrect are at the extremes and why is X (the total) used in the middle to carry out the weighted average calculation.
User avatar
TestPrepUnlimited
Joined: 17 Sep 2014
Last visit: 30 Jun 2022
Posts: 1,224
Own Kudos:
1,111
 [1]
Given Kudos: 6
Location: United States
GMAT 1: 780 Q51 V45
GRE 1: Q170 V167
Expert
Expert reply
GMAT 1: 780 Q51 V45
GRE 1: Q170 V167
Posts: 1,224
Kudos: 1,111
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
Each student at a certain Mathematics exam either solved the hardest problem correctly or incorrectly. What percent of the examinees solved the hardest problem correctly?

(1) The average score of those students who solved the hardest problem correctly was 12 more than the average score of all students.
(2) The average score of those students who solved the hardest problem incorrectly was 3 less than the average score of all students.


Are You Up For the Challenge: 700 Level Questions

First, let's combine the information as the answer is obviously either C or E.

Let the percent of examinees who solved the hardest problem correctly be X. Then (1-X) percent did not solve it correctly.

Think of this as the scenario where we deduct the average score from every examinee. Then the students in statement 1 have an average score of 12, the students in statement 2 have an average score of -3. The total average would be 0. With this information we can come up with the equation: 12 * X - 3*(1 - X) = 0.

This equation uses the average score as a reference.

We may solve for X with the equation above so combined sufficient.

Ans: C
User avatar
crimson_noise
Joined: 14 May 2024
Last visit: 19 Nov 2025
Posts: 29
Own Kudos:
6
 [1]
Given Kudos: 5
GMAT Focus 1: 615 Q80 V85 DI77
Products:
GMAT Focus 1: 615 Q80 V85 DI77
Posts: 29
Kudos: 6
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I haven't used the weighted average method but just created a equation for the average using information from both the options. I believe this is the quickest solution.
Attachment:
IMG_2512.jpg
IMG_2512.jpg [ 1.76 MiB | Viewed 279 times ]
Moderators:
Math Expert
105389 posts
496 posts