GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 18 Feb 2019, 02:59

GMAT Club Daily Prep

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

Events & Promotions

Events & Promotions in February
PrevNext
SuMoTuWeThFrSa
272829303112
3456789
10111213141516
17181920212223
242526272812
Open Detailed Calendar
• Valentine's day SALE is on! 25% off.

February 18, 2019

February 18, 2019

10:00 PM PST

11:00 PM PST

We don’t care what your relationship status this year - we love you just the way you are. AND we want you to crush the GMAT!
• Get FREE Daily Quiz for 2 months

February 18, 2019

February 18, 2019

10:00 PM PST

11:00 PM PST

Buy "All-In-One Standard ($149)", get free Daily quiz (2 mon). Coupon code : SPECIAL A paint crew gets a rush order to paint 80 houses in a new  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics Author Message TAGS: Hide Tags Senior Manager Joined: 14 Jul 2005 Posts: 389 A paint crew gets a rush order to paint 80 houses in a new [#permalink] Show Tags 21 Aug 2006, 00:38 4 38 00:00 Difficulty: 65% (hard) Question Stats: 70% (03:22) correct 30% (03:24) wrong based on 795 sessions HideShow timer Statistics A paint crew gets a rush order to paint 80 houses in a new development. They paint the first y houses at a rate of x houses per week. Realizing that they'll be late at this rate, they bring in some more painters and paint the rest of the houses at the rate of 1.25x houses per week. The total time it takes them to paint all the houses under this scenario is what fraction of the time it would have taken if they had painted all the houses at their original rate of x houses per week? (A) 0.8(80 – y) (B) 0.8 + 0.0025y (C) 80/y – 1.25 (D) 80/1.25y (E) 80 – 0.25y Most Helpful Community Reply Current Student Joined: 18 Oct 2014 Posts: 841 Location: United States GMAT 1: 660 Q49 V31 GPA: 3.98 Re: A paint crew gets a rush order to paint 80 houses in a new [#permalink] Show Tags 19 May 2016, 10:50 7 2 4 Original Time taken to finish the job with normal rate= 80/x hrs time taken to paint y houses with rate of x houses/week= y/x Time taken to paint remaining (80-y) houses with rate of 1.25 houses/week = 80-y/1.25x Total new time = y/x + 80-y/1.25x Fraction = New time/original time y/x + 80-y/1.25x/80/x= .25y +80/80 = 0.8 + 0.0025y B is the answer _________________ I welcome critical analysis of my post!! That will help me reach 700+ General Discussion Senior Manager Joined: 20 Feb 2006 Posts: 363 Show Tags 21 Aug 2006, 01:19 1 Time for painting houses at mixed rate= (t1) 80-y/1.25x + y/x = 320-4y/5x + y/x or 320-4y/5x + 5y/5x Simplified = 320 + y/5x Time for painting houses at constant rate = 80/x (t2) t1/t2 = 320+y/5x * x/80 ----> 32+y/400 or 0.8 + 0.0025y Intern Joined: 22 Jan 2006 Posts: 3 Re: MGMAT - Question of the week [#permalink] Show Tags 21 Aug 2006, 05:09 1 gmatornot wrote: Rush Paint Job A paint crew gets a rush order to paint 80 houses in a new development. They paint the first y houses at a rate of x houses per week. Realizing that they'll be late at this rate, they bring in some more painters and paint the rest of the houses at the rate of 1.25x houses per week. The total time it takes them to paint all the houses under this scenario is what fraction of the time it would have taken if they had painted all the houses at their original rate of x houses per week? (A) 0.8(80 â€“ y) (B) 0.8 + 0.0025y (C) 80/y â€“ 1.25 (D) 80/1.25y (E) 80 â€“ 0.25y original time = 80/x weeks new time = y/x + (80-y)/1.25x ratio=y/x + (80-y)/1.25x : 80/x = 1.25y+80 - y:100 = 0.25y+80:100 ratio = 0.8 0.0025y answer = B VP Joined: 02 Jun 2006 Posts: 1195 Show Tags 21 Aug 2006, 07:49 2 2 (B) 0.8 + 0.0025y Pretty straightforward question... @ x houses/wk , 80 houses time = 80/x weeks ... (1) @ x houses/wk, y houses time = y/x weeks ... (2) @ 1.25x houses/wk, (80-y) houses, time = (80-y)/1.25x weeks...(3) Adding (2) & (3): time = (y+320)/5x .... (4) Ratio of (4)/(1) = ((y+320)/5x) x (x/80) = 0.08 + 0.0025y Answer B. Senior Manager Joined: 11 Nov 2005 Posts: 303 Location: London Show Tags 21 Aug 2006, 09:54 1 B. BY TAKING ARBITARARY VALUE FOR X AND Y, LETS SAY Y = 20, X = 4, and then plug in number of x and y, upi get 0.85, which is the same as in B. Senior Manager Joined: 14 Jul 2005 Posts: 389 Show Tags 22 Aug 2006, 21:33 Answer is B.. Great job everyone ! Senior Manager Joined: 13 May 2013 Posts: 422 Re: A paint crew gets a rush order to paint 80 houses in a new [#permalink] Show Tags 20 May 2013, 08:55 1 I am working on a similar problem with a few differences. Can anyone help? "A painting crew painted 80 houses. They painted the first y houses at a rate of x houses per week. Then more painters arrived and everyone worked together to paint the remaining houses at a rate of 1.25x houses per week. How many weeks did it take to paint all 80 houses in terms of x and y? The answer is (y+320)/5x I decided to find the time it took by adding T1 and T2 (y/x and [80-y]\1.25x respectively) but I'm stuck past there. Does anyone know how I can solve this? Intern Joined: 08 Aug 2011 Posts: 10 GMAT Date: 04-04-2013 Re: A paint crew gets a rush order to paint 80 houses in a new [#permalink] Show Tags 21 May 2013, 07:30 2 Quote: I am working on a similar problem with a few differences. Can anyone help? "A painting crew painted 80 houses. They painted the first y houses at a rate of x houses per week. Then more painters arrived and everyone worked together to paint the remaining houses at a rate of 1.25x houses per week. How many weeks did it take to paint all 80 houses in terms of x and y? The answer is (y+320)/5x I decided to find the time it took by adding T1 and T2 (y/x and [80-y]\1.25x respectively) but I'm stuck past there. Does anyone know how I can solve this? To answer questions such as this one, I do a chart that helps me organizing information R * T = W Few Painters x T(1) = y -------------------------------------- All painters 1.25x T(2) = (80 - y)/1.25x What is the question? The question ask you to find how many weeks did it take to paint all 80 houses in terms of x and y? So in other terms what is T(1)+T(2)? Simply rearrange the term T(1) and T(2) T(1) + T (2) = y/x + (80 - y)/1.25x T(1) + T (2) = (1.25y + 80 - y)/1.25x ==> I put everything under the same denominator T(1) + T (2) = (0.25y + 80)/1.25x T(1) + T (2) = (0.25y*4 +80*4)/1.25x*4 ==> Multiply by 4/4 T(1) + T (2) = (y+320)/5x Here the "hard" part is to rearrange the term so that it matches the correct answer. Hope it helps, Intern Joined: 19 Jun 2014 Posts: 10 Re: A paint crew gets a rush order to paint 80 houses in a new [#permalink] Show Tags 15 Aug 2014, 07:13 This may be a case of bad numberpicking but it worked for me. 80 houses. Let's say that y=40 houses are painted at the rate x=10 houses per week <=> 1/10 week per house. 40*1/10 = 4 houses per week will be painted at this rate. 80-y = 80-40 = 40 houses are to be painted at the faster rate. X*1,25=12,5 houses per week <=> 1/12,5 weeks per house * 40 houses = 40/12,5 = 80/25 = 320/100 = 3,2 weeks. Which means finishing all houses at normal rate => 2*4 = 8 weeks. Faster rate = 4+3,2 = 7,2 weeks. 7,2/8 = 9/10 = 0,9. Insert y=40 in equations and it is clear that only (B) gives us 0,9. 0,8 + 0,0025*40 = 0,8 + 0,1 = 0,9. Manager Joined: 20 Mar 2015 Posts: 58 A paint crew gets a rush order to paint 80 houses in a new [#permalink] Show Tags 19 May 2016, 10:10 WholeLottaLove wrote: I am working on a similar problem with a few differences. Can anyone help? "A painting crew painted 80 houses. They painted the first y houses at a rate of x houses per week. Then more painters arrived and everyone worked together to paint the remaining houses at a rate of 1.25x houses per week. How many weeks did it take to paint all 80 houses in terms of x and y? The answer is (y+320)/5x I decided to find the time it took by adding T1 and T2 (y/x and [80-y]\1.25x respectively) but I'm stuck past there. Does anyone know how I can solve this? After doing calculations and looking at my answer and the available answer choices, I came to the following conclusion. It took me around 10 minutes to solve the problem. Well, math is not my background but no excuses, since GMAT doesn't tests your math skills. I wonder what will I do in exam. I can't waste 10 minutes for a question and I have roughly 1 month for the exam. Anyway, the answer is not $$\frac{(y+ 320)}{5x}$$ rather $$\frac{(y + 320)}{5x}$$ /$$\frac{80}{x}$$ Now, tricky part is here. $$\frac{(y + 320)}{5x}$$ $$*$$ $$\frac{x}{80}$$ = $$\frac{y + 320}{400}$$ =$$\frac{y}{400}$$ + $$\frac{320}{400}$$ =$$\frac{1}{400}$$ $$*$$ $$y + 0.8$$ $$\frac{1}{400}$$= 0.0025 therefore, ANS. is B Bunuel Is there a simple way to solve? chetan2u Is there a simple way to solve? Intern Joined: 15 Mar 2017 Posts: 1 Re: A paint crew gets a rush order to paint 80 houses in a new [#permalink] Show Tags 19 Mar 2017, 14:25 Hello everyone, thank you for the asnwers. However, I do not understand the last step of the equation. Why do we divide new time on the original time? I did not really get the question tbh... VP Joined: 09 Mar 2016 Posts: 1286 Re: A paint crew gets a rush order to paint 80 houses in a new [#permalink] Show Tags 15 May 2018, 10:39 MBAlad wrote: Time for painting houses at mixed rate= (t1) 80-y/1.25x + y/x = 320-4y/5x + y/x or 320-4y/5x + 5y/5x Simplified = 320 + y/5x Time for painting houses at constant rate = 80/x (t2) t1/t2 = 320+y/5x * x/80 ----> 32+y/400 or 0.8 + 0.0025y Hello pushpitkc could you write step by step how we from this 80-y/1.25x + y/x we get this 320 + y/5x is this combined rate ? and how we get this t1/t2 = 320+y/5x * x/80 ----> 32+y/400 is this combined time ? thank you Senior PS Moderator Joined: 26 Feb 2016 Posts: 3341 Location: India GPA: 3.12 A paint crew gets a rush order to paint 80 houses in a new [#permalink] Show Tags 15 May 2018, 11:34 1 dave13 wrote: MBAlad wrote: Time for painting houses at mixed rate= (t1) 80-y/1.25x + y/x = 320-4y/5x + y/x or 320-4y/5x + 5y/5x Simplified = 320 + y/5x Time for painting houses at constant rate = 80/x (t2) t1/t2 = 320+y/5x * x/80 ----> 32+y/400 or 0.8 + 0.0025y Hello pushpitkc could you write step by step how we from this 80-y/1.25x + y/x we get this 320 + y/5x is this combined rate ? and how we get this t1/t2 = 320+y/5x * x/80 ----> 32+y/400 is this combined time ? thank you Hey dave13 $$\frac{80-y}{1.25x} + \frac{y}{x} = \frac{4(80-y) + 5y}{5x}$$ (Here, the LCM of 1.25x and x is 5x) This can be further simplified as $$\frac{320 - 4y + 5y}{5x} = \frac{320 + y}{5x}$$ If the painters had painted the houses at a constant rate, time taken would be 80/x So, the ratio of the time taken is $$\frac{\frac{320+y}{5x}}{\frac{80}{x}}$$ , which when simplified becomes $$\frac{320+y}{5x}* \frac{x}{80} = \frac{320 + y}{400}$$ Hope this helps you! _________________ You've got what it takes, but it will take everything you've got Manager Joined: 07 Jun 2018 Posts: 109 A paint crew gets a rush order to paint 80 houses in a new [#permalink] Show Tags 24 Jul 2018, 03:38 2 Not fair, not fair! How did we get from here: (y/x)+(80-y)/1.25x : 80/x . . . . . . To here: 0.8 + 0.0025y I'll really appreciate a break down of the solving please, thanks! Senior Manager Joined: 04 Aug 2010 Posts: 345 Schools: Dartmouth College Re: A paint crew gets a rush order to paint 80 houses in a new [#permalink] Show Tags 01 Feb 2019, 06:40 gmatornot wrote: A paint crew gets a rush order to paint 80 houses in a new development. They paint the first y houses at a rate of x houses per week. Realizing that they'll be late at this rate, they bring in some more painters and paint the rest of the houses at the rate of 1.25x houses per week. The total time it takes them to paint all the houses under this scenario is what fraction of the time it would have taken if they had painted all the houses at their original rate of x houses per week? (A) 0.8(80 – y) (B) 0.8 + 0.0025y (C) 80/y – 1.25 (D) 80/1.25y (E) 80 – 0.25y Let y=0, implying that NONE of the 80 houses are painted at the original rate of x houses per week, with the result that ALL 80 houses are painted at the greater rate of (5/4)x houses per week. The total time it takes them to paint all the houses under this scenario is what fraction of the time it would have taken if they had painted all the houses at their original rate? Time and rate have a RECIPROCAL RELATIONSHIP. Since the rate for painting all 80 houses is 5/4 the original rate, the time for painting all 80 houses is 4/5 of the original time. The correct answer must yield 4/5 when y=0. Only B works: 0.8 + 0.0025y = 0.8 = 4/5. _________________ GMAT and GRE Tutor Over 1800 followers Click here to learn more GMATGuruNY@gmail.com New York, NY If you find one of my posts helpful, please take a moment to click on the "Kudos" icon. Available for tutoring in NYC and long-distance. For more information, please email me at GMATGuruNY@gmail.com. EMPOWERgmat Instructor Status: GMAT Assassin/Co-Founder Affiliations: EMPOWERgmat Joined: 19 Dec 2014 Posts: 13546 Location: United States (CA) GMAT 1: 800 Q51 V49 GRE 1: Q170 V170 Re: A paint crew gets a rush order to paint 80 houses in a new [#permalink] Show Tags 01 Feb 2019, 15:35 1 Hi All, We're told that a paint crew gets a rush order to paint 80 houses in a new development. They paint the first Y houses at a rate of X houses per week. Realizing that they'll be late at this rate, they bring in some more painters and paint the rest of the houses at the rate of 1.25X houses per week. We're asked to find the total time it takes them to paint all the houses under this scenario as a fraction of the time it would have taken if they had painted all the houses at their original rate of X houses per week. This question can be solved in a number of different ways, including by TESTing VALUES (and the answer choices are written in such a way that you don't have to do too much math overall to answer the question). To start, we should choose a value for X that will work well with 1.25X. Let's choose X = 4 (so 1.25X = 5). In addition, we should look to choose a value for Y that will leave a remaining number of house that will be a multiple of 5... Let's TEST... X = 4 Y = 20 For the first 20 houses, painting 4 houses/week will take 20/4 = 5 weeks. For the remaining 60 houses, painting 5 houses/week will take 60/5 = 12 weeks. Total time = 5 + 12 = 17 weeks At the original rate, the 80 houses would take 80/4 = 20 weeks. Thus, we're looking for a fraction that equals 17/20 = .85.... notice how that answer is a number that is LESS than 1. Considering how the answer choices are written, and that our Y = 20, you should be able to eliminate all of the wrong answers without doing too much math... Answer A: (.8)(60) --> greater than 1 Answer B: (.8) + a tiny decimal --> exactly what we're looking for! Answer C: 80/20 - 1.25 --> a little less than 3 Answer D: (80)/(1.25)(20) = 80/25 --> greater than 1 Answer E: (80) - (.25)(20) --> greater than 1 Final Answer: GMAT assassins aren't born, they're made, Rich _________________ 760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com Rich Cohen Co-Founder & GMAT Assassin Special Offer: Save$75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

*****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!*****

Re: A paint crew gets a rush order to paint 80 houses in a new   [#permalink] 01 Feb 2019, 15:35
Display posts from previous: Sort by

A paint crew gets a rush order to paint 80 houses in a new

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.