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.
It appears that you are browsing the GMAT Club forum unregistered!
Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club
Registration gives you:
Tests
Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.
Applicant Stats
View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more
Books/Downloads
Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!
Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
At exactly what time past 7:00 will the minute and hour [#permalink]
11 Jul 2003, 18:41
1
This post received KUDOS
28
This post was BOOKMARKED
00:00
A
B
C
D
E
Difficulty:
85% (hard)
Question Stats:
59% (03:35) correct
41% (02:59) wrong based on 349 sessions
At exactly what time past 7:00 will the minute and hour hands of an accurate working clock be precisely perpendicular to each other for the first time?
(A) 20 13/21 minutes past 7:00 (B) 20 13/17 minutes past 7:00 (C) 21 3/23 minutes past 7:00 (D) 21 9/11 minutes past 7:00 (E) 22 4/9 minutes past 7:00
AkamaiBrah Former Senior Instructor, Manhattan GMAT and VeritasPrep Vice President, Midtown NYC Investment Bank, Structured Finance IT MFE, Haas School of Business, UC Berkeley, Class of 2005 MBA, Anderson School of Management, UCLA, Class of 1993
Re: At exactly what time past 7:00 will the minute and hour [#permalink]
11 Jul 2003, 21:06
Sorry. Guessing not allowed. Show me how you solved it.
(It is NOT that hard if you take the right approach).
Motto: Spoonfed knowledge is not well retained, but knowledge worked hard for will be cherished for a long time.... _________________
Best,
AkamaiBrah Former Senior Instructor, Manhattan GMAT and VeritasPrep Vice President, Midtown NYC Investment Bank, Structured Finance IT MFE, Haas School of Business, UC Berkeley, Class of 2005 MBA, Anderson School of Management, UCLA, Class of 1993
Re: At exactly what time past 7:00 will the minute and hour [#permalink]
11 Jul 2003, 23:04
210 + M/12 - M = 90
Let M be the degrees covered by minute hand from zero. (7:00 pm is the reference point)
initially difference is 210 deg. Hour hand will move at the rate of M/12, so after M minutes hour hand will be at 210+M/12 and minute hand will be at M. The difference should be 90. Find M and divide by 6, which will give you the minutes.
Re: At exactly what time past 7:00 will the minute and hour [#permalink]
12 Jul 2003, 07:49
The answer is D. Evensflow did it the fastest although all of the solutions were fine. The key is computing the rate of each hand and solving for when they are 90 deg apart.
Good job all. _________________
Best,
AkamaiBrah Former Senior Instructor, Manhattan GMAT and VeritasPrep Vice President, Midtown NYC Investment Bank, Structured Finance IT MFE, Haas School of Business, UC Berkeley, Class of 2005 MBA, Anderson School of Management, UCLA, Class of 1993
At exactly what time past 7:00 will the minute and hour [#permalink]
03 Sep 2014, 12:33
6
This post received KUDOS
4
This post was BOOKMARKED
At 7:00, hour hand must be at 210 degree from 12 (clock wise). Minute hand of the clock moves with 6 degree per minute speed and hour hand moves at 1/2 degree per minute. Therefore in x min hour hand will travel (1/2)*x degree further 210 degree from initial position; meanwhile minute hand must cover 6x degrees. Difference between minute and hour hand is required 90 degree. Formed following equation and solved for x.
Piyush K ----------------------- Our greatest weakness lies in giving up. The most certain way to succeed is to try just one more time. ― Thomas A. Edison Don't forget to press--> Kudos My Articles: 1. WOULD: when to use?| 2. All GMATPrep RCs (New) Tip: Before exam a week earlier don't forget to exhaust all gmatprep problems specially for "sentence correction".
At exactly what time past 7:00 will the minute and hour [#permalink]
12 May 2015, 13:02
Anotehr way to solve this problem is to use the formula that we have for the angle of the clock needels.
\(angle of clock needels =\frac{(60H + 11M)}{2}\) where H is the hour and the M is the minutes. We can imply that the H= 7 because the strating point is 7:00 any way and just need to find the M in the equation with making teh equation equal to 90 since that is what is being asked. Do the math and you will see that \(M=21\frac{9}{11}\)
So not bad to learn the formula at beggiging I was struguling with teh question and trying to go figure out some other stuff, but than I remmeberd on this formula and applied it.
Re: At exactly what time past 7:00 will the minute and hour [#permalink]
20 May 2015, 19:10
1
This post was BOOKMARKED
PiyushK wrote:
At 7:00, minute hand must be at 210 degree from 12 (clock wise). Minute hand of the clock moves with 6 degree per minute speed and hour hand moves at 1/2 degree per minute. Therefore in x min hour hand will travel (1/2)*x degree further 210 degree from initial position; meanwhile minute hand must cover 6x degrees. Difference between minute and hour hand is required 90 degree. Formed following equation and solved for x.
Re: At exactly what time past 7:00 will the minute and hour [#permalink]
19 Sep 2015, 17:34
I solved this problem in this way:
We know that: hour indicator moves 5 minutes every 60 minutes -->1/12 to minute indicator moves 1 minute every minute-->1/1 And that to be parallel they need to be 15 minutes awa from each other....then because the hour time is at 7hrs=35min and at 0 for minutes.
(35+t/12) reflects the position after t minutes of the hour indicator. t reflect the position of the minutes indcator after t minutes.
Re: At exactly what time past 7:00 will the minute and hour [#permalink]
30 Jan 2016, 07:14
AkamaiBrah wrote:
At exactly what time past 7:00 will the minute and hour hands of an accurate working clock be precisely perpendicular to each other for the first time?
(A) 20 13/21 minutes past 7:00 (B) 20 13/17 minutes past 7:00 (C) 21 3/23 minutes past 7:00 (D) 21 9/11 minutes past 7:00 (E) 22 4/9 minutes past 7:00
5.5 is the angle between minute n hour, this is what I was taught...so shouldn't it be solve by dividing 90 with 5.5?
At exactly what time past 7:00 will the minute and hour [#permalink]
30 Jan 2016, 07:27
1
This post received KUDOS
baharemustafa wrote:
AkamaiBrah wrote:
At exactly what time past 7:00 will the minute and hour hands of an accurate working clock be precisely perpendicular to each other for the first time?
(A) 20 13/21 minutes past 7:00 (B) 20 13/17 minutes past 7:00 (C) 21 3/23 minutes past 7:00 (D) 21 9/11 minutes past 7:00 (E) 22 4/9 minutes past 7:00
5.5 is the angle between minute n hour, this is what I was taught...so shouldn't it be solve by dividing 90 with 5.5?
That would have been the case if your initial difference between the hour and the minute hand was = 0 degrees or in other words, both minute and hour hands were at the same location. But as per the question, you are asked for time AFTER 7:00. At 7:00, the angle between the hour and the minute hand is 210 degrees. you need to take this into account as well.
So in order for the difference to decrease to 90 degrees, the minute hand must eat away this difference of 210-90 = 120 degree at the rate of 5.5 degrees per minute ---> 120/5.5 = 21 9/11 minutes.
Thus, D is the correct answer.
Hope this helps.
P.S.: If what you are saying was correct, then you should have calculated 16 4/11 minutes and this is not present in the given options. This should have told you that you are making a mistake somewhere. _________________
Re: At exactly what time past 7:00 will the minute and hour [#permalink]
30 Jan 2016, 09:55
Engr2012 wrote:
baharemustafa wrote:
AkamaiBrah wrote:
At exactly what time past 7:00 will the minute and hour hands of an accurate working clock be precisely perpendicular to each other for the first time?
(A) 20 13/21 minutes past 7:00 (B) 20 13/17 minutes past 7:00 (C) 21 3/23 minutes past 7:00 (D) 21 9/11 minutes past 7:00 (E) 22 4/9 minutes past 7:00
5.5 is the angle between minute n hour, this is what I was taught...so shouldn't it be solve by dividing 90 with 5.5?
That would have been the case if your initial difference between the hour and the minute hand was = 0 degrees or in other words, both minute and hour hands were at the same location. But as per the question, you are asked for time AFTER 7:00. At 7:00, the angle between the hour and the minute hand is 210 degrees. you need to take this into account as well.
So in order for the difference to decrease to 90 degrees, the minute hand must eat away this difference of 210-90 = 120 degree at the rate of 5.5 degrees per minute ---> 120/5.5 = 21 9/11 minutes.
Thus, D is the correct answer.
Hope this helps.
P.S.: If what you are saying was correct, then you should have calculated 16 4/11 minutes and this is not present in the given options. This should have told you that you are making a mistake somewhere.
thanks mate.....yeah this is the reason why I had asked....
gmatclubot
Re: At exactly what time past 7:00 will the minute and hour
[#permalink]
30 Jan 2016, 09:55
The “3 golden nuggets” of MBA admission process With ten years of experience helping prospective students with MBA admissions and career progression, I will be writing this blog through...
You know what’s worse than getting a ding at one of your dreams schools . Yes its getting that horrid wait-listed email . This limbo is frustrating as hell . Somewhere...