BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Darlene and her averages

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 941
Joined: Sun Dec 27, 2009 12:28 am
Thanked: 20 times
Followed by:1 members

Darlene and her averages

by bhumika.k.shah » Sun Jan 31, 2010 3:21 am
Darlene averaged a score of 70 out of 110 on evaluations from 1/3 of her supervisors. If Darlene wishes to average a score of 90 out of 110 on all of her evaluations, by approximately what percent must her average score increase on the remaining 2/3 of the evaluations?

A.20%
B.28%
C.32%
D.37%
E.43%
Top
Source: — Problem Solving |
User avatar
Legendary Member
Posts: 1275
Joined: Thu Sep 21, 2006 11:13 pm
Location: Arabian Sea
Thanked: 125 times
Followed by:2 members

by ajith » Sun Jan 31, 2010 3:27 am
bhumika.k.shah wrote:Darlene averaged a score of 70 out of 110 on evaluations from 1/3 of her supervisors. If Darlene wishes to average a score of 90 out of 110 on all of her evaluations, by approximately what percent must her average score increase on the remaining 2/3 of the evaluations?

A.20%
B.28%
C.32%
D.37%
E.43%
Say there are 3 judges and one gave 70/110 to Darlene
To average 90/110 she needs a total of 270/110
That is an average of 200/220 or 100/110 from the rest of the judges

score increase = 30/70*100 = 43%
Always borrow money from a pessimist, he doesn't expect to be paid back.
Top
Legendary Member
Posts: 941
Joined: Sun Dec 27, 2009 12:28 am
Thanked: 20 times
Followed by:1 members

by bhumika.k.shah » Sun Jan 31, 2010 10:46 am
how much time did this take you to solve???
ajith wrote:
bhumika.k.shah wrote:Darlene averaged a score of 70 out of 110 on evaluations from 1/3 of her supervisors. If Darlene wishes to average a score of 90 out of 110 on all of her evaluations, by approximately what percent must her average score increase on the remaining 2/3 of the evaluations?

A.20%
B.28%
C.32%
D.37%
E.43%
Say there are 3 judges and one gave 70/110 to Darlene
To average 90/110 she needs a total of 270/110
That is an average of 200/220 or 100/110 from the rest of the judges

score increase = 30/70*100 = 43%
Top
User avatar
Legendary Member
Posts: 1275
Joined: Thu Sep 21, 2006 11:13 pm
Location: Arabian Sea
Thanked: 125 times
Followed by:2 members

by ajith » Sun Jan 31, 2010 10:48 am
bhumika.k.shah wrote:how much time did this take you to solve???
Well I think I can do it in less than 2 minutes but, it is a hunch feeling.
Always borrow money from a pessimist, he doesn't expect to be paid back.
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 241
Joined: Wed Jan 27, 2010 10:10 pm
Location: Chennai
Thanked: 23 times
Followed by:2 members
GMAT Score:690

by sars72 » Sun Jan 31, 2010 11:11 am
it becomes a whole let easier if you put it in an equation and simply the values

1/3rd gave 70 out of 110. what should 2/3 give to make it 90/110 can be written as follows:

(1/3)(70/110) + (2/3)x = 90/110

--> (1/3)(7/11) + (2/3)x = 9/11

--> (2/3) x = 9/11 - 7/33

--> (2/3)x = (27-7)/33 = 20/33

--> x= 60/66 = 10/11

Percentage Increase = [(10/11 - 7/11)/ 7/11] * 100% = 3/11 * 11/7 * 100 = 3/7 * 100 = 42. ... ~ 43%

Though the explanation looks long, I assure you that it will take you barely more than a minute.

Remember to memorize your fraction -> decimal conversions upto 1/20. This will save you a lot of time on the test.
Top
Legendary Member
Posts: 941
Joined: Sun Dec 27, 2009 12:28 am
Thanked: 20 times
Followed by:1 members

by bhumika.k.shah » Sun Jan 31, 2010 11:15 am
Though the explanation looks long, I assure you that it will take you barely more than a minute.

I agree. :-)

i am glad i understood a different approach! :-)
Top
Legendary Member
Posts: 941
Joined: Sun Dec 27, 2009 12:28 am
Thanked: 20 times
Followed by:1 members

by bhumika.k.shah » Sun Jan 31, 2010 11:16 am
[quote="sars72"

Remember to memorize your fraction -> decimal conversions upto 1/20. This will save you a lot of time on the test.[/quote]

hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm
Top
User avatar
Legendary Member
Posts: 2109
Joined: Sun Apr 19, 2009 10:25 pm
Location: New Jersey
Thanked: 109 times
Followed by:79 members
GMAT Score:640

by money9111 » Sun Jan 31, 2010 12:11 pm
i completed this the same way that sars72 did... it seems confusing at first, but when you break it down and realize it's all just regular / fractional multiplication it's not that bad...
My goal is to make MBA applicants take onus over their process.

My story from Pre-MBA to Cornell MBA - New Post in Pre-MBA blog

Me featured on Poets & Quants

Free Book for MBA Applicants

Top
Junior | Next Rank: 30 Posts
Posts: 11
Joined: Wed Sep 02, 2009 6:06 am
Thanked: 1 times

by aakar » Tue Feb 02, 2010 11:21 am
Maybe this is the wrong way to do the problem, but this is how I went about it...

I ignored the fact that we're dealing with 70/110 and 90/110 and just took it as 70 and 90.

Determined that for her to get a 90 average her total should be 3 * 90 = 270

We've already been told that 1 of her managers gave her a 70: 270-70 = 200
2 of her managers are left and she needs to average a 100 on both to get a 90.

Percent Increase = (100-70)/70 = 3/7 = ~43%

Thoughts?
Top
User avatar
Legendary Member
Posts: 526
Joined: Sat Feb 21, 2009 11:47 pm
Location: India
Thanked: 68 times
GMAT Score:680

by harshavardhanc » Tue Feb 02, 2010 12:04 pm
aakar wrote:Maybe this is the wrong way to do the problem, but this is how I went about it...

I ignored the fact that we're dealing with 70/110 and 90/110 and just took it as 70 and 90.

Determined that for her to get a 90 average her total should be 3 * 90 = 270

We've already been told that 1 of her managers gave her a 70: 270-70 = 200
2 of her managers are left and she needs to average a 100 on both to get a 90.

Percent Increase = (100-70)/70 = 3/7 = ~43%

Thoughts?
It's not wrong at all!

That's the freedom we can use when we just have averages (e.g 70 & 90) , fractions in variables(e.g 1/3 & 2/3) and percentages .
Regards,
Harsha
Top
Legendary Member
Posts: 941
Joined: Sun Dec 27, 2009 12:28 am
Thanked: 20 times
Followed by:1 members

by bhumika.k.shah » Tue Feb 02, 2010 7:07 pm
i like :-)

simple to understand! :-)

quote="aakar"]Maybe this is the wrong way to do the problem, but this is how I went about it...

I ignored the fact that we're dealing with 70/110 and 90/110 and just took it as 70 and 90.

Determined that for her to get a 90 average her total should be 3 * 90 = 270

We've already been told that 1 of her managers gave her a 70: 270-70 = 200
2 of her managers are left and she needs to average a 100 on both to get a 90.

Percent Increase = (100-70)/70 = 3/7 = ~43%

Thoughts?[/quote]
Top
Newbie | Next Rank: 10 Posts
Posts: 3
Joined: Wed Jan 25, 2012 2:48 am

by Pavan M » Mon Mar 05, 2012 7:20 am
I found a new way of doing this problem.

Given 70 of 110 evaluation at 1/3 observations so -- 70*x*110/3*100 -- 77x/3

Desired 90 of 110 evaluations at 2/3 observations so -- 90*2x*100/3*100 -- 191x/3

what % does the average score increase on her 2/3 oberservations

So -- 191x/3 - 77x/3 = 43.3x (remember we have already divided both the equations by 100 so the answer now is directly 43.3%)
Top
Senior | Next Rank: 100 Posts
Posts: 92
Joined: Thu Oct 06, 2011 8:06 am
Thanked: 18 times

by Neo Anderson » Mon Mar 05, 2012 10:59 am
agree with all the above posts, but i think allegation is the easiest way:

as we need to calculate the increase( take 70 as the base)


Image

=> (x-20)/20 = 1/2 => x = 30
Top
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Tue Mar 06, 2012 3:42 am
bhumika.k.shah wrote:Darlene averaged a score of 70 out of 110 on evaluations from 1/3 of her supervisors. If Darlene wishes to average a score of 90 out of 110 on all of her evaluations, by approximately what percent must her average score increase on the remaining 2/3 of the evaluations?

A.20%
B.28%
C.32%
D.37%
E.43%
Let the number of supervisors = 3.
The sum of the 3 scores = number*average = 3*90 = 270.
The number of supervisors who gave a score of 70 = (1/3)3 = 1.
The sum of the scores of the other 2 supervisors = 270-70 = 200.
Average score from these 2 supervisors = sum/number = 200/2 = 100.
Percent increase from 70 to 100 = Difference/Original * 100 = 30/70 * 100 ≈ 43.

The correct answer is E.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Junior | Next Rank: 30 Posts
Posts: 18
Joined: Wed Feb 29, 2012 4:52 am
Thanked: 5 times
Followed by:1 members

by kohsamed » Tue Mar 06, 2012 7:43 am
Hi guys, I am new to GMAT but confused on this one.

I read the question as:

She has 70/110 (63%) so far, and needs 100/110 (91%) from the remaining 2/3 to hit her desired average of 90/110.

91-63 = 28?

Given everyone interpreted the q differently, i am obviously wrong. is there some wording that i have not picked up on?
Top
Post new topic Post Reply
• Page 1 of 1