Author 
Message 
TAGS:

Hide Tags

GMAT Forum Moderator
Joined: 27 May 2014
Posts: 429

4 Bells toll together at 9:00 A.M. They toll after 7, 8, 11 and 12 sec [#permalink]
Show Tags
02 Feb 2017, 18:53
3
This post was BOOKMARKED
Question Stats:
55% (01:50) correct 45% (02:38) wrong based on 56 sessions
HideShow timer Statistics
4 Bells toll together at 9:00 A.M. They toll after 7, 8, 11 and 12 seconds respectively. How many times will they toll together again in the next 3 hours? (A) 3 (B) 4 (C) 5 (D) 6 (E) 7
Official Answer and Stats are available only to registered users. Register/ Login.



SC Moderator
Joined: 13 Apr 2015
Posts: 1581
Location: India
Concentration: Strategy, General Management
WE: Analyst (Retail)

Re: 4 Bells toll together at 9:00 A.M. They toll after 7, 8, 11 and 12 sec [#permalink]
Show Tags
02 Feb 2017, 20:09
1
This post was BOOKMARKED
All 4 bells toll together at LCM(7, 8, 11, 12) = 1848 secs
3 hours = 3600 * 3 = 10800 secs
Number of times = 10800/1848 > 5 times
Answer: C



Board of Directors
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 3326
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)

Re: 4 Bells toll together at 9:00 A.M. They toll after 7, 8, 11 and 12 sec [#permalink]
Show Tags
03 Feb 2017, 10:45
saswata4s wrote: 4 Bells toll together at 9:00 A.M. They toll after 7, 8, 11 and 12 seconds respectively. How many times will they toll together again in the next 3 hours? (A) 3 (B) 4 (C) 5 (D) 6 (E) 7 9:00 AM + LCM ( 7, 8, 11 & 12 ) => 9:00 AM + 1848/60 Min = 9:00 AM +30.80 min So, The sequence will be 9:00 AM , 9:31 AM , 10 : 02 AM , 10:33 AM, 11:04 AM , 11: 35 AM... Thus, in the 3 hours, the bells will toll together 5 times... Hence, answer will be (C) 5
_________________
Thanks and Regards
Abhishek....
PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS
How to use Search Function in GMAT Club  Rules for Posting in QA forum  Writing Mathematical Formulas Rules for Posting in VA forum  Request Expert's Reply ( VA Forum Only )



Manager
Joined: 19 Oct 2016
Posts: 75
Location: India
Concentration: Marketing, Leadership
GMAT 1: 580 Q46 V24 GMAT 2: 540 Q39 V25 GMAT 3: 660 Q48 V34
GPA: 3.15
WE: Psychology and Counseling (Health Care)

Re: 4 Bells toll together at 9:00 A.M. They toll after 7, 8, 11 and 12 sec [#permalink]
Show Tags
04 Feb 2017, 00:16
saswata4s wrote: 4 Bells toll together at 9:00 A.M. They toll after 7, 8, 11 and 12 seconds respectively. How many times will they toll together again in the next 3 hours? (A) 3 (B) 4 (C) 5 (D) 6 (E) 7 This is not a sub600 level question I'm afraid. To find the LCM of 7, 8, 11, and 12 makes this question roughly an 800 level question. Easy processing but finding the LCM for these 4 numbers is immensely difficult. Reminder: think before you post question difficulty and follow the guidelines



Senior Manager
Joined: 06 Dec 2016
Posts: 253

Re: 4 Bells toll together at 9:00 A.M. They toll after 7, 8, 11 and 12 sec [#permalink]
Show Tags
20 Mar 2017, 15:00
Another approach to solve this The LCM of 7, 8, 11 and 12 seconds is 1848 seconds
Therefore 1848/60 = 30.80
180/30.80 is obviously lower than 6 since 180/30 = 6
Therefore, the answer is C



Senior Manager
Joined: 05 Jan 2017
Posts: 434
Location: India

Re: 4 Bells toll together at 9:00 A.M. They toll after 7, 8, 11 and 12 sec [#permalink]
Show Tags
21 Mar 2017, 02:14
saswata4s wrote: 4 Bells toll together at 9:00 A.M. They toll after 7, 8, 11 and 12 seconds respectively. How many times will they toll together again in the next 3 hours? (A) 3 (B) 4 (C) 5 (D) 6 (E) 7 They will toll again after every LCM (7,8,11,12) = 1848 second no. of times the bell will ring in 3 hrs = 10800 seconds = 10800/1848 = 5.8 or 5 times adding the first time we get the total no as 6 times.




Re: 4 Bells toll together at 9:00 A.M. They toll after 7, 8, 11 and 12 sec
[#permalink]
21 Mar 2017, 02:14






