Author 
Message 
TAGS:

Hide Tags

Intern
Joined: 18 Sep 2010
Posts: 2

A software programmer does 20% of the work in 80% of the
[#permalink]
Show Tags
Updated on: 05 Nov 2012, 22:27
Question Stats:
69% (03:03) correct 31% (03:06) wrong based on 440 sessions
HideShow timer Statistics
A software programmer does 20% of the work in 80% of the time, and 80% of the work in the remaining 20% of the time. If the code he writes is X lines long and he was given one month (30 days) to accomplish the task, then, assuming that the programmer works at a constant rate in each of the two stages, How many lines of code were written in the last two weeks, in terms of X? A. 13x /15 B. 15x/15 C. 7x/15 D. 2x/30 E. 13x/30
Official Answer and Stats are available only to registered users. Register/ Login.
Originally posted by vivatran on 06 Mar 2011, 05:42.
Last edited by vivatran on 05 Nov 2012, 22:27, edited 3 times in total.




Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8386
Location: Pune, India

Re: Work Problems
[#permalink]
Show Tags
15 Sep 2011, 22:27
shuwa wrote: A software programmer does 20% of the work in 80% of the time, and 80% of the work in the remaining 20% of the time. If the code he writes is X lines long and he was given one month (30 days) to accomplish the task, then, assuming that the programmer works at a constant rate in each of the two stages, How many lines of code were written in the last two weeks, in terms of X?
A) 13x /15
B) 15x/15
C) 7x/15
D) 2x/30
E) 13x/30 Another thing you might want to note here is that he does 80% of the work in the last 20% of time i.e. in last 6 days. So the work he does in last 14 days is more than 4X/5 but less than X. Only option (A) lies in this range.
_________________
Karishma Veritas Prep GMAT Instructor
Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >
GMAT selfstudy has never been more personalized or more fun. Try ORION Free!




Retired Moderator
Joined: 20 Dec 2010
Posts: 1835

Re: Work Problems
[#permalink]
Show Tags
06 Mar 2011, 05:54
30 days X lines 80% of 30 24 days; 0.2X lines Remaining 6 days: 0.8X lines Need to find out for last 14 days; We know the number of lines for last 6 days: 0.8X How about 8 days before that; 24 days 0.2X 1 day  0.2X/24 lines 8 days  (0.2X/24)*8 lines = (1/15)X lines Total number of lines in last 14 days (1/15)x + 0.8X = (1/15)x + (8/10)X = (52/60)X = (13/15)X lines of codes
_________________
~fluke
GMAT Club Premium Membership  big benefits and savings




Math Expert
Joined: 02 Sep 2009
Posts: 49968

Re: Work Problems
[#permalink]
Show Tags
06 Mar 2011, 06:35
shuwa wrote: A software programmer does 20% of the work in 80% of the time, and 80% of the work in the remaining 20% of the time. If the code he writes is X lines long and he was given one month (30 days) to accomplish the task, then, assuming that the programmer works at a constant rate in each of the two stages, How many lines of code were written in the last two weeks, in terms of X?
Please explain. thanks It's better to plug the numbers for this question let x=30 lines; 20% of the work in 80% of the time > 0.2*30 lines=6 lines in the first 0.8*30 days=24 days and the remaining 24 lines in last 6 days; Last 14 days = last 6 days (stage 2) + previous 8 days (part of stage 1): 24 lines in last 6 days + 1/3*6=2 lines in previous 8 days (as 8 is 1/3 of 24 days in stage 1) = 26 lines in the last 14 days, which is 26/30=13/15 part of the whole job. P.S. Please provide answer choices for PS problems.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Retired Moderator
Joined: 16 Nov 2010
Posts: 1437
Location: United States (IN)
Concentration: Strategy, Technology

Re: Work Problems
[#permalink]
Show Tags
06 Mar 2011, 23:25
X lines  work 30 days  time 0.2x lines of code in 24 days So in 1 day lines of code written = 0.2x/24 0.8x lines of code written in 6 days So lines of code written in last 2 weeks = 0.2x/24 * 8 + 0.8x = 0.2x/3 + 0.8x = 0.2x( 1/3 + 4) = 2/10 * 13/3 * x = 13/15x
_________________
Formula of Life > Achievement/Potential = k * Happiness (where k is a constant)
GMAT Club Premium Membership  big benefits and savings



Intern
Joined: 27 Feb 2011
Posts: 41

Re: Work Problems
[#permalink]
Show Tags
06 Mar 2011, 23:41
guys.. I think there are two answers to this problem ..
Solution 1: explained above: the dude works for 24 days and then 6 days..
Solution 2: he can also do 80% in first 6 days and then 20% in the next 24 days..
the last 2 weeks fall in 24 days..
24 days = 0.2 * X 14 days = 0.2 * X * 14 / 24 = 7 X/ 60



Director
Joined: 01 Feb 2011
Posts: 668

Re: Work Problems
[#permalink]
Show Tags
18 Sep 2011, 10:16
work  time
1 t 20/100 80t/100 80/100 20t/100
task
30 days  x lines
20x/100 will be finished in (80/100)*30 days ( i.e 24 days)
80x/100 in (20/100)*30 days (i.e 6 days)
work done in last two weeks = last 6 days work + last 8 days work
= 80x/100 + (20x/100)(8/24) = 13x/15
(one flaw i see in the question is that it does not say the programmer works initial 20% of work in 80% time. so if you take it as initial 80% of work in 20% time, answer would be different)



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8386
Location: Pune, India

Re: Work Problems
[#permalink]
Show Tags
18 Sep 2011, 21:06
Spidy001 wrote: (one flaw i see in the question is that it does not say the programmer works initial 20% of work in 80% time. so if you take it as initial 80% of work in 20% time, answer would be different)
I did notice the same thing and therefore, read the question stem carefully. Notice that it says 'does 20% of the work in 80% of the time, and 80% of the work in the remaining 20% of the time.' Important is the use of the word 'remaining' which implies that he does 20% of the work in the first 80% of time and 80% in the leftover 20% time. Therefore, the intent of the question is quite clear.
_________________
Karishma Veritas Prep GMAT Instructor
Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >
GMAT selfstudy has never been more personalized or more fun. Try ORION Free!



Intern
Joined: 01 Nov 2010
Posts: 8
Location: United States
GMAT Date: 03302012
WE: Pharmaceuticals (Health Care)

Re: Work Problems
[#permalink]
Show Tags
21 Sep 2011, 20:10
Hi, I'm trying to plug in for Question # 138 in OG 12. Could anyone point out where i'm going wrong in my reasoning? No. of Boxes loaded by Night workers = 3/4 of Day workers No. of Night workers = 4/5 of Day workers. Let the number of Day workers = 100 and they load a total of 100 boxes. No. of boxes loaded by Night workers = 3/4 x 100 = 75 No. of Night workers = 4/5 x 100 = 80 total no. of boxes loaded by both workers = 175 total no. of boxes loaded by day workers = 100 fraction of boxes loaded by day workers out of the total = 100/175 = 4/7 The closest answer is 4/5 which is D. But the correct answer is 5/8 which is E.



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8386
Location: Pune, India

Re: Work Problems
[#permalink]
Show Tags
22 Sep 2011, 20:51
gmatyro wrote: Hi, I'm trying to plug in for Question # 138 in OG 12. Could anyone point out where i'm going wrong in my reasoning? No. of Boxes loaded by Night workers = 3/4 of Day workers No. of Night workers = 4/5 of Day workers. Let the number of Day workers = 100 and they load a total of 100 boxes. No. of boxes loaded by Night workers = 3/4 x 100 = 75 No. of Night workers = 4/5 x 100 = 80 total no. of boxes loaded by both workers = 175 total no. of boxes loaded by day workers = 100 fraction of boxes loaded by day workers out of the total = 100/175 = 4/7 The closest answer is 4/5 which is D. But the correct answer is 5/8 which is E. You need to make a new thread for a new question, put down the question and your method.
_________________
Karishma Veritas Prep GMAT Instructor
Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >
GMAT selfstudy has never been more personalized or more fun. Try ORION Free!



Intern
Joined: 01 Nov 2010
Posts: 8
Location: United States
GMAT Date: 03302012
WE: Pharmaceuticals (Health Care)

Re: Work Problems
[#permalink]
Show Tags
23 Sep 2011, 13:19
VeritasPrepKarishma wrote: gmatyro wrote: Hi, I'm trying to plug in for Question # 138 in OG 12. Could anyone point out where i'm going wrong in my reasoning? No. of Boxes loaded by Night workers = 3/4 of Day workers No. of Night workers = 4/5 of Day workers. Let the number of Day workers = 100 and they load a total of 100 boxes. No. of boxes loaded by Night workers = 3/4 x 100 = 75 No. of Night workers = 4/5 x 100 = 80 total no. of boxes loaded by both workers = 175 total no. of boxes loaded by day workers = 100 fraction of boxes loaded by day workers out of the total = 100/175 = 4/7 The closest answer is 4/5 which is D. But the correct answer is 5/8 which is E. You need to make a new thread for a new question, put down the question and your method. Hi, There was a thread already and have posted the question on that thread. [url]helpmewiththeanswerratesratioquestion102404.html[/url] I went thru the answers posted which i understand but i can't see why my reasoning is wrong. Appreciate your response



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8386
Location: Pune, India

Re: Work Problems
[#permalink]
Show Tags
24 Sep 2011, 09:48
gmatyro wrote: Hi, There was a thread already and have posted the question on that thread. [url]helpmewiththeanswerratesratioquestion102404.html[/url] I went thru the answers posted which i understand but i can't see why my reasoning is wrong. Appreciate your response
Have posted the issue in your solution in that thread itself. If you want me to look at a particular question or your solution, just put it down in the corresponding thread and send me a pm. I will look into it.
_________________
Karishma Veritas Prep GMAT Instructor
Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >
GMAT selfstudy has never been more personalized or more fun. Try ORION Free!



Intern
Joined: 24 Sep 2011
Posts: 7

Re: Work Problems
[#permalink]
Show Tags
24 Sep 2011, 16:41
Hi,
Is there a way to solve the problem by solving for the portion of X done in the first 14 days and subtract the result from X? I keep getting the wrong answer with the following:
X/5 = R*4T/5 R = X/(4T) 14 days later.. or T/2 X/(4T)*T/2 = X/8 So for the remainder period... XX/8 = 7X/8
would appreciate any help that would pinpoint where this fails.



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8386
Location: Pune, India

Re: Work Problems
[#permalink]
Show Tags
29 Sep 2011, 03:23
syh244 wrote: Hi,
Is there a way to solve the problem by solving for the portion of X done in the first 14 days and subtract the result from X? I keep getting the wrong answer with the following:
X/5 = R*4T/5 R = X/(4T) 14 days later.. or T/2 X/(4T)*T/2 = X/8 So for the remainder period... XX/8 = 7X/8
would appreciate any help that would pinpoint where this fails. Sure you can do it that way too. The error is that the month consists of 30 days (given) so you need to find the work done in 16 days (so that 2 weeks i.e. 14 days are leftover) and subtract that from X. (X/4T) * 16T/30 = 2X/15 X  2X/15 = 13X/15
_________________
Karishma Veritas Prep GMAT Instructor
Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >
GMAT selfstudy has never been more personalized or more fun. Try ORION Free!



Manager
Joined: 21 Aug 2010
Posts: 175
Location: United States

Re: Work Problems
[#permalink]
Show Tags
04 Oct 2011, 10:01
There are two portion for this problem I. First 80% of time  24 days (20% work) II. Remaining 20% time  6 days (80% work) The amount of work done in last two weeks(14 days) = 8 days of period 1 and 6 days of period 2 work done in 8 days of period 1 = 1/3(20%) = 6.66% Work done in last two days = 6.66 + 80 = 86.66 = 13/15 in terms of x 13x/15
_________________




Math Expert
Joined: 02 Sep 2009
Posts: 49968

Re: A software programmer does 20% of the work in 80% of the
[#permalink]
Show Tags
19 Feb 2012, 02:45



Manager
Joined: 16 Jan 2011
Posts: 101

Re: A software programmer does 20% of the work in 80% of the
[#permalink]
Show Tags
13 Apr 2012, 04:21
taking into account the assumptions about 20% of work during the 80% of time and vice versa we get
(1) 30 days*80%=24days X work *20%=x/5 (2) 30*20%=6 days X*80%=4x/5 we need to find out the amount of work, done during the last 14 days according to the (2) we already have the amount of work, done in last 6 days  4x/5
rest will be calculated based on the data from (1) knowing that during each stage work was done at constant rate, we can set a proportion (x/5)/24*8=x/15
and now we just sum up two pieces of work x/15+(4x)/5=13x/15



Manager
Joined: 26 Mar 2012
Posts: 52
Concentration: Social Entrepreneurship, Strategy
GPA: 3.7

Re: A software programmer does 20% of the work in 80% of the
[#permalink]
Show Tags
18 Jun 2012, 17:48
Just another way to look at it: 20% done in 80% of time 80% done in 20% of time So we need the full "80% done in 20% time" > 80% done of X > 0.8(X)Now the time where he was slacking in the beginning... 20% done in 80% time. We are only concerned with 30% of this time (50% was in the first half, we only want the duration that spills over into the second half. 80% 50% = 30% of the second half). So, 20% of 30% = 6% = .06(X)Now we are done. Total of .86X was completed [add both portions, .06X+.8X] which is equal to 13(X)/15 (also easy to eyeball from the question answers).
_________________
That 700.. I can taste it



Director
Joined: 03 Aug 2012
Posts: 755
Concentration: General Management, General Management
GMAT 1: 630 Q47 V29 GMAT 2: 680 Q50 V32
GPA: 3.7
WE: Information Technology (Investment Banking)

Re: A software programmer does 20% of the work in 80% of the
[#permalink]
Show Tags
28 Sep 2013, 03:02
Must say Good question !
Number of lines = X = 900
Then
First 24 days(80% of time) = 180 lines (per day = 7.5) last 6 days (20 % of time) = 720 lines
8 days from First 24 days = 8 * 7.5 lines = 60 lines Last 6 days = 720 lines
8+6 days = 2 weeks => 780 Lines
hence (A) substituting X=900



Intern
Joined: 14 Dec 2011
Posts: 16
Location: India
Concentration: Technology, Nonprofit
GMAT 1: 640 Q48 V29 GMAT 2: 660 Q45 V35
GPA: 3.5
WE: Information Technology (Computer Software)

Re: A software programmer does 20% of the work in 80% of the
[#permalink]
Show Tags
13 Oct 2013, 20:41
vivatran wrote: A software programmer does 20% of the work in 80% of the time, and 80% of the work in the remaining 20% of the time. If the code he writes is X lines long and he was given one month (30 days) to accomplish the task, then, assuming that the programmer works at a constant rate in each of the two stages, How many lines of code were written in the last two weeks, in terms of X?
A. 13x /15 B. 15x/15 C. 7x/15 D. 2x/30 E. 13x/30 Take X=30 lines 80% of 30 = 24 lines 20% of 30 = 6 lines W  R  T 6 lines  r1  24 (first 80% of the 30 days) 24 lines  r2  6 ( last 20% of the 20 days) r1 = 1/4 & r2 = 4 Now Work in last 14 days = 6 days programmer worked at r2 + 8days programmer worked at r1 => 6 * 4 + 8 * 1/4 = 24 + 2 = 26 Insert, X=30 in all options => A is the answer.




Re: A software programmer does 20% of the work in 80% of the &nbs
[#permalink]
13 Oct 2013, 20:41



Go to page
1 2
Next
[ 26 posts ]



