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 350,000 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:

Re: easy one but cant solve it [#permalink]
07 Dec 2010, 04:01

2

This post received KUDOS

Expert's post

1

This post was BOOKMARKED

xcusemeplz2009 wrote:

If a,b,c,d are each +ve, a+b+c+d=8, a^2+b^2+c^2+d^2=25 and c=d ..Then what is the greatest value of c..? (A)1/2 (B) 3/2 (C) 5/2 (D) 7/2

oa soon

This is not a GMAT question so I wouldn't worry about it at all. Anyway below is an algebraic solution for it:

Given: a+b+2c=8 and a^2+b^2+2c^2=25.

a+b+2c=8 --> b=8-a-2c --> a^2+(8-a-2c)^2+2c^2=25 --> 2a^2+4a(c-4)+(6c^2-32c+39)=0. Now, this quadratic equation to have real solutions for a its discriminat must be more than or equal to zero: d=4^2*(c-4)^2-4*2(6c^2-32c+39)\geq{0} --> 4c^2-16c+7\leq{0} --> {\frac{1}{2}}\leq{c}\leq{\frac{7}{2}} --> c_{max}=\frac{7}{2}.

Re: easy one but cant solve it [#permalink]
07 Dec 2010, 18:43

1

This post received KUDOS

Expert's post

nikhilpoddar wrote:

can this be a gmat prob ???

GMAT problems sometimes look tricky. Nevertheless, all of them can be easily solved. Something like this isn't fun to do.. just tedious... so very slim chance that it will appear on GMAT... If you do get stuck on something, don't fret. Use options. Here try 7/2 since it is the greatest value. Make d also 7/2 and split the leftover 1 from the sum of 8 evenly between a and b. It will work. It is not a neat little problem but still intuitive. _________________

Re: If a, b, c, d are each positive, a+b+c+d=8, a^2+b^2+c^2+d^2= [#permalink]
17 Aug 2013, 12:32

I tried hit and trial method.

let a= 1 b=2 c=3

1+2+6=9 a^2 + b^2 + 2 c^2= 1 + 4 + 18 = 23

c should be near to 3 and 7/2 is the nearest value. Its not a foolproof way, but good to guess a possible answer _________________

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".

gmatclubot

Re: If a, b, c, d are each positive, a+b+c+d=8, a^2+b^2+c^2+d^2=
[#permalink]
17 Aug 2013, 12:32

Wow...I'm still reeling from my HBS admit . Thank you once again to everyone who has helped me through this process. Every year, USNews releases their rankings of...

Almost half of MBA is finally coming to an end. I still have the intensive Capstone remaining which started this week, but things have been ok so far...