Last visit was: 05 Sep 2026, 23:44 It is currently 05 Sep 2026, 23:44
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
705-805 (Hard)|   Word Problems|                        
User avatar
Fdambro294
Joined: 10 Jul 2019
Last visit: 27 Jun 2026
Posts: 1,324
Own Kudos:
Given Kudos: 1,656
Posts: 1,324
Kudos: 787
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
Sabby
Joined: 17 Jun 2018
Last visit: 04 Mar 2026
Posts: 84
Own Kudos:
Given Kudos: 396
Location: France
GPA: 3.85
Posts: 84
Kudos: 126
Kudos
Add Kudos
Bookmarks
Bookmark this Post
avatar
Quynhsatoh
Joined: 01 Mar 2022
Last visit: 13 Apr 2024
Posts: 5
Given Kudos: 16
Location: Viet Nam
GMAT 1: 690 Q46 V46
GRE 1: Q161 V161
GMAT 1: 690 Q46 V46
GRE 1: Q161 V161
Posts: 5
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
GMATinsight
User avatar
Major Poster
Joined: 08 Jul 2010
Last visit: 05 Sep 2026
Posts: 7,298
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: 7,298
Kudos: 17,484
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Find the easiest possible explanation of this question here...



Bunuel
A certain clock marks every hour by striking a number of times equal to the hour, and the time required for a stroke is exactly equal to the time interval between strokes. At 6:00 the time lapse between the beginning of the first stroke and the end of the last stroke is 22 seconds. At 12:00, how many seconds elapse between the beginning of the first stroke and the end of the last stroke?

(A) 72
(B) 50
(C) 48
(D) 46
(E) 44
User avatar
PGTLrowanhand
Joined: 30 Oct 2012
Last visit: 04 Sep 2026
Posts: 161
Own Kudos:
Given Kudos: 3
Status:London UK GMAT Consultant / Tutor
Expert
Expert reply
Posts: 161
Kudos: 189
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Here's my video solution:
User avatar
FrozenDragon
User avatar
DI Forum Moderator
Joined: 05 May 2023
Last visit: 25 Aug 2026
Posts: 409
Own Kudos:
Given Kudos: 497
GMAT Focus 1: 615 Q83 V81 DI78
Products:
GMAT Focus 1: 615 Q83 V81 DI78
Posts: 409
Kudos: 687
Kudos
Add Kudos
Bookmarks
Bookmark this Post
For better imagination of this question. I hope this helps :
Attachments

Gemini_Generated_Image_5pae8r5pae8r5pae.png
Gemini_Generated_Image_5pae8r5pae8r5pae.png [ 4.27 MiB | Viewed 70 times ]

User avatar
Usernamevisible
Joined: 09 Jun 2022
Last visit: 05 Sep 2026
Posts: 480
Own Kudos:
Given Kudos: 1,282
Products:
Posts: 480
Kudos: 111
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Key idea
The clock strikes a number of times equal to the hour.
So:
  • At 6:00 → 6 strikes
  • At 12:00 → 12 strikes


What does this sentence mean?
Quote:
"The time required for a stroke is exactly equal to the time interval between strokes."
Let:
  • Duration of one stroke = (x) seconds
  • Gap between consecutive strokes = (x) seconds
    This is because the problem explicitly says the time required for a stroke equals the interval between strokes.


Why isn't it just 5 gaps at 6:00?
The problem asks for the time from:
Quote:
the beginning of the first stroke to the end of the last stroke
So we must count:
  1. The time spent making the strokes.
  2. The gaps between them.
    For 6 strikes:
    Stroke Gap Stroke Gap Stroke Gap Stroke Gap Stroke Gap Stroke
  • 6 strokes
  • 5 gaps
    Therefore:
    Total time = 6x + 5x = 11x
    Given:
    11x = 22
    x = 2


At 12:00
For 12 strikes:
  • 12 strokes
  • 11 gaps
    So:
    Total time = 12x + 11x = 23x
    Substitute (x = 2):
    23 × 2 = 46


Answer
46
Option (D)
Shortcut
For (n) strikes:
  • Strokes = n
  • Gaps = n − 1
    Total time from beginning of first stroke to end of last stroke:
    n + (n − 1) = 2n − 1
    pieces of length (x).
    So:
  • At 6:00 → ((2 × 6 − 1)x = 11x = 22)
  • At 12:00 → ((2 × 12 − 1)x = 23x = 46)

bicu17
I don't understand the interval part in the explanations. How do you come up with 5 intervals? Why do you add them together?
Thanks.
   1   2 
Moderator:
Math Expert
113155 posts