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:

One kilogram of a certain coffee blend consists of x [#permalink]

Show Tags

25 Mar 2012, 11:23

2

This post received KUDOS

39

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

95% (hard)

Question Stats:

42% (02:44) correct
58% (01:50) wrong based on 1029 sessions

HideShow timer Statistics

One kilogram of a certain coffee blend consists of x kilogram of type I coffee and y kilogram of type II coffee. The cost of the blend is C dollars per kilogram, where C = 6.5x + 8.5y. Is x < 0.8?

One kilogram of a certain coffee blend consists of x kilogram of type I coffee and y kilogram of type II coffee. The cost of the blend is C dollars per kilogram, where C = 6.5x + 8.5y. Is x < 0.8?

"One kilogram of a certain coffee blend consists of x kilogram of type I coffee and y kilogram of type II coffee"

So, \(x+y=1\). Question: is \(x<0.8\).

(1) y > 0.15 --> \(1-x>0.15\) --> \(x<0.85\). Not sufficient.

I tried doing this via using the concept of weighted average. Its given in statement 2 that 6.5x + 8.5y>=7.3. Now, when x=.5 and y=.5, then the c would be 7.5. (GIVEN FACT IS THAT X+Y=1.) Total distance in terms of parts is 2 units and in terms of numerical distance is 1. For every 2 part change, there is a 0.1 deviation in the numerical separation. Since c>=7.3( note the 0.2 deviation), the numerical deviation is 0.1. Hence x must be <=0.6. Regards.
_________________

Re: One kilogram of a certain coffee blend consists of x [#permalink]

Show Tags

01 May 2013, 16:39

1

This post received KUDOS

x+y=1 c= 6.5x + 8.5y Question ---- is x<0.8 ?

As seen from above equations , for a given sum of x and y ( =1) , the value of C increases as x decreases and Y increases ( since y is multipled by greater number than x)

If x=0.8 , then y=0.2 and C= (6.5*0.8) + (8.5*0.2) = 6.9 .

Now if we increase value of x above 0.8 , the value of C decreases below 6.9 ( consider x=0.9 , then y would be 0.1 , which pulls down the value of C below 6.9--- as per the highlighted text above). And if we decrease the value of x below 0.8 , the value of c increases from 6.9 ( cos y is increased when x is reduced).

Statement 1 - y>0.15 , Y could be 0.2 , in which case x=0.8 ( No to the answer) or Y = 0.3 , in which case x=0.7 ( yes to the answer) Insufficient

Statement 2 C>=7.5 , as seen from above , for any c > 6.9 demands a x <0.8 . Hence sufficient.

Re: One kilogram of a certain coffee blend consists of x [#permalink]

Show Tags

03 May 2013, 21:29

It is really nice to find this place as it is full of fun. Looking forward for new friends. Hope I'll definitely enjoy my stay here. ood question and quite a learning...

Out of curiousity, can this sum be solved in less than 2mins that too under "GMAT exam" conditions that too at first sight??

One kilogram of a certain coffee blend consists of x kilogram of type I coffee and y kilogram of type II coffee. The cost of the blend is C dollars per kilogram, where C = 6.5x + 8.5y. Is x < 0.8?

(1) y > 0.15

(2) C >= 7.30

Responding to a pm:

Quote:

I could solve most of the problems using the scale method, though I was finding it difficult to solve this particular question using it.

C = Avg cost of the mix = Cost of the blend = 6.5x + 8.5y

If you remember your weighted average formula, Avg = (C1*w1 + C2*w2)/(w1 + w2) = Avg Cost = (C1*x + C2*y)/(x + y) (x+y) is 1 kg since the weight of the blend is 1 kg. Avg Cost = C = (C1*x + C2*y) = (6.5x + 8.5y) So cost of type I coffee is $6.5/kg and cost of type II coffee is $8.5/kg.

So everything is set for you. All you have to do is plug in the values of x and y now. Question: Is x > 0.8?

(1) y > 0.15 If y is 0.16, x is 0.84 If y is 0.5, x is 0.5 This statement alone is not sufficient.

(2) C >= 7.30 Let's say C = 7.3 x/y = (8.5 - 7.3)/(7.3 - 6.5) = 12/8 = 3/2 (The Scale Method) x = 3/5 = 0.6 If C is greater than 7.3, x/y will get smaller and hence the value of x will keep getting smaller too. Say if C = 7.5, x/y = 1/1 x = 0.5 and so on...

So x can be at most 0.6. Hence it must be less than 0.8. Statement II alone is sufficient.

Re: One kilogram of a certain coffee blend consists of x [#permalink]

Show Tags

16 Sep 2013, 04:15

1

This post received KUDOS

Idk, in my opinion after you figure out that x+y=1 and that C=6.5x+8.5y (knowing that C can be 7.30), we have two equations and we can solve for X. Please correct me if I'm wrong but this was my line of reasoning and I've chosen B after 1min.

Re: One kilogram of a certain coffee blend consists of x [#permalink]

Show Tags

21 Apr 2014, 01:09

Initially I got the answer wrong but there was a calculation mistake. I am posting my approach anyway :D,

Question Says, One kilogram of a certain coffee blend consists of x kilogram of type I coffee and y kilogram of type II coffee. The cost of the blend is C dollars per kilogram, where C = 6.5x + 8.5y. Is x < 0.8?

(1) y > 0.15

(2) C >= 7.30

Sol. x + y = 1 (from question statement) now, cost C = 6.5x + 8.5y = 6.5 (x + y) + 2y = 6.5 +2y------(eq. 1) we need to check whether x < 0.8 or y > 0.2 (since x + y = 1)

option 1). y > 0.15 clearly not sufficient alone.

option 2). C >= 7.30 from eq.1, 6.5 + 2y >= 7.30 => 2y => 0.80 => y>= 0.40 or x =< 0.60 Hence, sufficient.

One kilogram of a certain coffee blend consists of x [#permalink]

Show Tags

12 Jan 2015, 05:22

One kilogram of a certain coffee blend consists of x kilogram of type I coffee and y kilogram of type II coffee. The cost of the blend is C dollars per kilogram, where C = 6.5x + 8.5y. Is x < 0.8?

Re: One kilogram of a certain coffee blend consists of x [#permalink]

Show Tags

12 Jan 2015, 05:43

1

This post received KUDOS

With x+y = 1, we can simplify the equation for C:

C = 6.5 + 2y

Statement 1: Not sufficient. x can still be anywhere between 0 and 0.85

Statement 2: Sufficient: 7.3 = 6.5 + 2y. This leads to y = 0.4 and x smaller than 0.8. If C is greater than 7.3, this will only increase y and therefore decrease x, which will therefore be smaller than 0.8 in any case.

Answer B.
_________________

\(\sqrt{-1}\) \(2^3\) \(\Sigma\) \(\pi\) ... and it was delicious!

Re: One kilogram of a certain coffee blend consists of x [#permalink]

Show Tags

12 Jan 2015, 06:21

superjohn5566 wrote:

One kilogram of a certain coffee blend consists of x kilogram of type I coffee and y kilogram of type II coffee. The cost of the blend is C dollars per kilogram, where C = 6.5x + 8.5y. Is x < 0.8?

One kilogram of a certain coffee blend consists of x kilogram of type I coffee and y kilogram of type II coffee. The cost of the blend is C dollars per kilogram, where C = 6.5x + 8.5y. Is x < 0.8?

(1) y > 0.15

(2) C >= 7.30

Merging similar topics. Please refer to the solutions above.
_________________

Re: One kilogram of a certain coffee blend consists of x [#permalink]

Show Tags

04 Apr 2016, 01:53

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

Best Schools for Young MBA Applicants Deciding when to start applying to business school can be a challenge. Salary increases dramatically after an MBA, but schools tend to prefer...

Marty Cagan is founding partner of the Silicon Valley Product Group, a consulting firm that helps companies with their product strategy. Prior to that he held product roles at...