Problem from GMATprep
This topic has expert replies
-
- Junior | Next Rank: 30 Posts
- Posts: 25
- Joined: Wed Nov 17, 2010 7:54 am
- Thanked: 1 times
Guys need help, the attachment contains problem from GMAT prep software with correct answers. I would like the explanation for each.
- Attachments
-
- math.doc
- (4.39 MiB) Downloaded 71 times
GMAT/MBA Expert
- Anju@Gurome
- GMAT Instructor
- Posts: 511
- Joined: Wed Aug 11, 2010 9:47 am
- Location: Delhi, India
- Thanked: 344 times
- Followed by:86 members
Please try to post the problems in words so that people can search them later and do not post so many problems in one thread. It'll be a mess if different people have doubts in different solutions.
Also most of the GMATPrep problems have been discussed in this forum quite a number of times. Just use the search facility of the forum; It is likely that you will get a solution that suits you.
I'll post the solution of first problem only.
Make separate threads for other problems if you cannot find their solutions.
Sufficient
Statement 2: The average (arithmetic mean) volume of water in the tanks at the end of the experiment was 63 gallons does not help in finding the standard deviation of the volumes of water in the tanks at the end of the experiment.
Not sufficient.
The correct answer is A.
Also most of the GMATPrep problems have been discussed in this forum quite a number of times. Just use the search facility of the forum; It is likely that you will get a solution that suits you.
I'll post the solution of first problem only.
Make separate threads for other problems if you cannot find their solutions.
Statement 1: If we multiply or divide all the elements by same constant, standard deviation changes by the magnitude of the constant. As it is given that 30% of the volume of water is removed from all the tanks, the standard deviation will also decrease by 30%.During an experiment, some was removed from each of 6 water tanks. If the standard deviation of the volumes of water in the tanks at the beginning of the experiment was 10 gallons, what was the standard deviation of the volumes of water in the tanks at the end of the experiment?
1. For each tank, 30 percent of the volume of water that was in the tank at the beginning of the experiment was removed during the experiment.
2. The average(arithmetic mean) volume of water in the tanks at the end of the experiment was 63 gallons.
Sufficient
Statement 2: The average (arithmetic mean) volume of water in the tanks at the end of the experiment was 63 gallons does not help in finding the standard deviation of the volumes of water in the tanks at the end of the experiment.
Not sufficient.
The correct answer is A.
Last edited by Anju@Gurome on Tue Apr 16, 2013 11:49 pm, edited 1 time in total.
Anju Agarwal
Quant Expert, Gurome
Backup Methods : General guide on plugging, estimation etc.
Wavy Curve Method : Solving complex inequalities in a matter of seconds.
§ GMAT with Gurome § Admissions with Gurome § Career Advising with Gurome §
Quant Expert, Gurome
Backup Methods : General guide on plugging, estimation etc.
Wavy Curve Method : Solving complex inequalities in a matter of seconds.
§ GMAT with Gurome § Admissions with Gurome § Career Advising with Gurome §
-
- Junior | Next Rank: 30 Posts
- Posts: 25
- Joined: Wed Nov 17, 2010 7:54 am
- Thanked: 1 times
- mariofelixpasku
- Senior | Next Rank: 100 Posts
- Posts: 41
- Joined: Sun Sep 23, 2012 4:26 am
- Thanked: 2 times
shouldnt the standard deviation change exact by that factor if we multiply each volume by the same factor ?
GMAT/MBA Expert
- Anju@Gurome
- GMAT Instructor
- Posts: 511
- Joined: Wed Aug 11, 2010 9:47 am
- Location: Delhi, India
- Thanked: 344 times
- Followed by:86 members
Yes. You are correct.mariofelixpasku wrote:shouldnt the standard deviation change exact by that factor if we multiply each volume by the same factor ?
I've edited my reply.
Anju Agarwal
Quant Expert, Gurome
Backup Methods : General guide on plugging, estimation etc.
Wavy Curve Method : Solving complex inequalities in a matter of seconds.
§ GMAT with Gurome § Admissions with Gurome § Career Advising with Gurome §
Quant Expert, Gurome
Backup Methods : General guide on plugging, estimation etc.
Wavy Curve Method : Solving complex inequalities in a matter of seconds.
§ GMAT with Gurome § Admissions with Gurome § Career Advising with Gurome §