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: What is the value of k [#permalink]
20 Sep 2010, 07:15

utin wrote:

I thought of solving this ques by forming an equation as =>10x+20y=k(x+y) =>x(10-k)=y(k-20) =>x/y=k-20/10-k now since x<y =>k-20<10-k =>2k<30 =>k<15

I know i am unable to reach a unique answer with this...but would like to know is there something else going wrong with this approach?

the step highlighted above is incorrect. This does not follow from x/y=(k-20)/(10-k) Eg. If x/y=2/3=(k-20)/(10-k) Now if k-20=2 then 20-k=3 so indeed your inequality holds But if k-20=-2 then 20-k=-3 so the inequality you have concluded is wrong

In general when manipulating around with inequalities you have to be very careful and be-ware that you are not implicitly assuming the positive or negative nature of any of the terms o/w you can get such wrong results _________________

Re: What is the value of k [#permalink]
20 Sep 2010, 18:22

tejal777 wrote:

I got that the expression reduces to: k =10(1+ y/x+y) Can somebody please elaborate after that?How are we getting values?

After this you need to think what values the expression y/(x+y) can take. Since x<y so x "limits to " y and expression can reach 0.5. So expression is greater than 0.5

x limits to 0 and expression can reach 1. So expression is smaller than 1. Hope this answers how we got the range.

Now 10 + 10 multiplied by range 0.5 to 1 will give you the limit. Pick answer choice fitting the range _________________

If you like my post, consider giving me some KUDOS !!!!! Like you I need them

Re: What is the value of k [#permalink]
21 Sep 2010, 16:26

The answer should be D

The way I thought about it was that k is made up of (x/x+y) percent of 10 and (y/x+y) percent of 20. That is how interpolation is done. Then since y is greater than x, you will have the number close to 20 than to 10. It also has to be between 20 and 10, since it is made up of certain percentages of these two number.

Originally posted on MIT Sloan School of Management : We are busy putting the final touches on our application. We plan to have it go live by July 15...