Author 
Message 
TAGS:

Hide Tags

Intern
Joined: 19 Dec 2009
Posts: 33

A contractor estimated that his 10man crew could complete t [#permalink]
Show Tags
08 Jan 2011, 12:20
1
This post received KUDOS
10
This post was BOOKMARKED
Question Stats:
52% (03:52) correct 48% (02:58) wrong based on 136 sessions
HideShow timer Statistics
A contractor estimated that his 10man crew could complete the construction in 110 days if there was no rain. (Assume the crew does not work on any rainy day and rain is the only factor that can deter the crew from working). However, on the 61st day, after 5 days of rain, he hired 6 more people and finished the project early. If the job was done in 100 days, how many days after day 60 had rain? A. 4 B. 5 C. 6 D. 7 E. 8
Official Answer and Stats are available only to registered users. Register/ Login.



Math Expert
Joined: 02 Sep 2009
Posts: 44599

Re: complicated work problem [#permalink]
Show Tags
08 Jan 2011, 12:33
rtaha2412 wrote: A contractor estimated that his 10man crew could complete the construction in 110 days if there was no rain. (Assume the crew does not work on any rainy day and rain is the only factor that can deter the crew from working). However, on the 61st day, after 5 days of rain, he hired 6 more people and finished the project early. If the job was done in 100 days, how many days after day 60 had rain?
4 5 6 7 8 Given: 10man crew needs 110 days to complete the construction. "On the 61st day, after 5 days of rain ..." > as it was raining for 5 days then they must have bee working for 55 days thus completed 1/2 of the job, 1/2 is left (55 days of work for 10 men). Then contractor "hired 6 more people" > speed of construction increased 1.6 times, so the new 16man crew needed 55/1.6=~34.4 days to complete the construction, but after they were hired job was done in 10060=40 days > so 5 days rained. (They needed MORE than 34 days to finish the job, so if it rained for 6 days they wouldn't be able to finish the job in 100(40) days.) Answer: B.
_________________
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



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8028
Location: Pune, India

Re: complicated work problem [#permalink]
Show Tags
08 Jan 2011, 20:21
rtaha2412 wrote: A contractor estimated that his 10man crew could complete the construction in 110 days if there was no rain. (Assume the crew does not work on any rainy day and rain is the only factor that can deter the crew from working). However, on the 61st day, after 5 days of rain, he hired 6 more people and finished the project early. If the job was done in 100 days, how many days after day 60 had rain?
4 5 6 7 8 You can visualize it in another way: 10 man crew needs 110 days means the total work = 10*110 = 1100 mandays (mandays means the amount of work 1 man does in 1 day) In 60 days, it rained for 5 days and the crew worked for 55 days and completed 10*55 = 550 mandays work and left over work is 1100  550 = 550 mandays From 61st day on, there are 16 people working and will need 550/16 = 34.4 days to complete the remaining work. So out of 40 days (from 61st to 100th day), 35 days were used (though the 100th day wasn't completely utilized) and it must have rained on 5 days.
_________________
Karishma Veritas Prep  GMAT Instructor My Blog
Get started with Veritas Prep GMAT On Demand for $199
Veritas Prep Reviews



Manager
Joined: 07 Jan 2010
Posts: 133
Location: So. CA
WE 1: 2 IT
WE 2: 4 Software Analyst

Re: complicated work problem [#permalink]
Show Tags
10 Jan 2011, 21:02
VeritasPrepKarishma wrote:
From 61st day on, there are 16 people working and will need 550/16 = 34.4 days to complete the remaining work. So out of 40 days (from 61st to 100th day), 35 days were used (though the 100th day wasn't completely utilized) and it must have rained on 5 days.
your method makes sense, but i got kind of lost at the end. so if it takes 34.4 days, wouldn't it be 61+34=95 days, so it rained for 5 days? thanks.



Math Expert
Joined: 02 Sep 2009
Posts: 44599

Re: complicated work problem [#permalink]
Show Tags
11 Jan 2011, 00:46
gtr022001 wrote: VeritasPrepKarishma wrote:
From 61st day on, there are 16 people working and will need 550/16 = 34.4 days to complete the remaining work. So out of 40 days (from 61st to 100th day), 35 days were used (though the 100th day wasn't completely utilized) and it must have rained on 5 days.
your method makes sense, but i got kind of lost at the end. so if it takes 34.4 days, wouldn't it be 61+34=95 days, so it rained for 5 days? thanks. Yes it rained on 5 days but the job took 34.4 days, so more than 34 (full 34 days and the part of 35th day). Next, you should count from 61st day (61st day is the first day when 16 men crew started to work) so 60+35=95 (not 61+...) > 10095=5.
_________________
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



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8028
Location: Pune, India

Re: complicated work problem [#permalink]
Show Tags
11 Jan 2011, 05:33
gtr022001 wrote: VeritasPrepKarishma wrote:
From 61st day on, there are 16 people working and will need 550/16 = 34.4 days to complete the remaining work. So out of 40 days (from 61st to 100th day), 35 days were used (though the 100th day wasn't completely utilized) and it must have rained on 5 days.
your method makes sense, but i got kind of lost at the end. so if it takes 34.4 days, wouldn't it be 61+34=95 days, so it rained for 5 days? thanks. As bunuel pointed out above, it rained for 5days in the first 60 days. Thereafter, in the remaining 100  60 = 40 days, they worked for 34.4 days ie 35 days (the 35th day, they worked partly). The rest of the 5 days, it rained. Snce the work was not over in 34 days, they needed the 35th day. You cannot round it off to 34.
_________________
Karishma Veritas Prep  GMAT Instructor My Blog
Get started with Veritas Prep GMAT On Demand for $199
Veritas Prep Reviews



Manager
Status: PLAY HARD OR GO HOME
Joined: 25 Feb 2014
Posts: 172
Location: India
Concentration: General Management, Finance
GPA: 3.1

Re: A contractor estimated that his 10man crew could complete t [#permalink]
Show Tags
19 Oct 2014, 07:41
2
This post received KUDOS
110 days * 10 workers= 1100 units of work in total.. 55 days of work done with help of 10 workers..therefore, 55 days * 10 workers = 550 units of work done..it means 550 units of work remaining.. It means, 550 units /16 workers = 34.3 days required to finish the work.. Since the work done in 100 days,we have 40 days remaining, but the days required are 34.3 or we can say 35 since,until 0.3 units of work is not completed,we cannot claim that work is completed.. Hence 5 days of work remain... Hope it helps..
_________________
ITS NOT OVER , UNTIL I WIN ! I CAN, AND I WILL .PERIOD.



Current Student
Joined: 18 Oct 2014
Posts: 886
Location: United States
GPA: 3.98

Re: A contractor estimated that his 10man crew could complete t [#permalink]
Show Tags
03 Jun 2016, 06:44
rtaha2412 wrote: A contractor estimated that his 10man crew could complete the construction in 110 days if there was no rain. (Assume the crew does not work on any rainy day and rain is the only factor that can deter the crew from working). However, on the 61st day, after 5 days of rain, he hired 6 more people and finished the project early. If the job was done in 100 days, how many days after day 60 had rain?
A. 4 B. 5 C. 6 D. 7 E. 8 10 men worked for 55 days. It rained from 56th to 60th day. On 61st day, he hired 6 more people, making total 16 people working. Since 10 men can complete total work in 110 days, they must have completed 1/2 work in first 55 days. From day 61 he had 16 workers working in remaining 1/2 work. Now, if 10 workers take 55 days to complete 1/2 work, 16 workers take 55*10/16= 34.3 days (34 days + next day= 35 days) But its given that they finished the work in 40 days (61st to 100th day). Hence they did not work on 4035= 5 days B is the answer
_________________
I welcome critical analysis of my post!! That will help me reach 700+



Senior Manager
Joined: 03 Apr 2013
Posts: 290
Location: India
Concentration: Marketing, Finance
GPA: 3

Re: A contractor estimated that his 10man crew could complete t [#permalink]
Show Tags
05 Dec 2017, 00:47
VeritasPrepKarishma wrote: rtaha2412 wrote: A contractor estimated that his 10man crew could complete the construction in 110 days if there was no rain. (Assume the crew does not work on any rainy day and rain is the only factor that can deter the crew from working). However, on the 61st day, after 5 days of rain, he hired 6 more people and finished the project early. If the job was done in 100 days, how many days after day 60 had rain?
4 5 6 7 8 You can visualize it in another way: 10 man crew needs 110 days means the total work = 10*110 = 1100 mandays (mandays means the amount of work 1 man does in 1 day) In 60 days, it rained for 5 days and the crew worked for 55 days and completed 10*55 = 550 mandays work and left over work is 1100  550 = 550 mandays From 61st day on, there are 16 people working and will need 550/16 = 34.4 days to complete the remaining work. So out of 40 days (from 61st to 100th day), 35 days were used (though the 100th day wasn't completely utilized) and it must have rained on 5 days. Following your approach, I did this, but the answer came out wrong. after 60 days have passed, the 16 member crew is able to do 550 mandays of work in 40 days. What would've happened if it worked for the 40 days? they would have done 640 mandys of work. But they did only 550 mandays of work. so they did not work for the number of days it would have taken them to do 640550 = 90 mandays of work 90/16 = 5.625 rounding off gives 6!
_________________
Spread some love..Like = +1 Kudos



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8028
Location: Pune, India

Re: A contractor estimated that his 10man crew could complete t [#permalink]
Show Tags
05 Dec 2017, 01:25
ShashankDave wrote: VeritasPrepKarishma wrote: rtaha2412 wrote: A contractor estimated that his 10man crew could complete the construction in 110 days if there was no rain. (Assume the crew does not work on any rainy day and rain is the only factor that can deter the crew from working). However, on the 61st day, after 5 days of rain, he hired 6 more people and finished the project early. If the job was done in 100 days, how many days after day 60 had rain?
4 5 6 7 8 You can visualize it in another way: 10 man crew needs 110 days means the total work = 10*110 = 1100 mandays (mandays means the amount of work 1 man does in 1 day) In 60 days, it rained for 5 days and the crew worked for 55 days and completed 10*55 = 550 mandays work and left over work is 1100  550 = 550 mandays From 61st day on, there are 16 people working and will need 550/16 = 34.4 days to complete the remaining work. So out of 40 days (from 61st to 100th day), 35 days were used (though the 100th day wasn't completely utilized) and it must have rained on 5 days. Following your approach, I did this, but the answer came out wrong. after 60 days have passed, the 16 member crew is able to do 550 mandays of work in 40 days. What would've happened if it worked for the 40 days? they would have done 640 mandys of work. But they did only 550 mandays of work. so they did not work for the number of days it would have taken them to do 640550 = 90 mandays of work 90/16 = 5.625 rounding off gives 6! The answer is the same  you need to use logic here to figure out whether you will round off to 5 or 6. Note that in my explanation above, I rounded off 34.4 days to 35 days. Why? Because they worked for a part of the 35th day too. The work got completed in 0.4 day but the 35th day was used. Hence it rained for 5 days only. You will use the same logic. 5.6 days were not used. It must have rained on 5 days and a part of the 6th day must have been used so it must not have rained on it.
_________________
Karishma Veritas Prep  GMAT Instructor My Blog
Get started with Veritas Prep GMAT On Demand for $199
Veritas Prep Reviews



Senior Manager
Joined: 03 Apr 2013
Posts: 290
Location: India
Concentration: Marketing, Finance
GPA: 3

Re: A contractor estimated that his 10man crew could complete t [#permalink]
Show Tags
05 Dec 2017, 01:31
Hi VeritasPrepKarishma, thank you for the prompt response. I understand your point. But considering what you have said, it would be needed to be specified by the question that if it rains for a portion of a day, the remaining time is used by the workers and that counts as a full day of work. Posted from my mobile device
_________________
Spread some love..Like = +1 Kudos



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8028
Location: Pune, India

Re: A contractor estimated that his 10man crew could complete t [#permalink]
Show Tags
05 Dec 2017, 01:37
ShashankDave wrote: Hi VeritasPrepKarishma, thank you for the prompt response. I understand your point. But considering what you have said, it would be needed to be specified by the question that if it rains for a portion of a day, the remaining time is used by the workers and that counts as a full day of work. Posted from my mobile deviceNo. The question tells you  "Assume the crew does not work on any rainy day " They worked partially on the last day because the work got over, not because it rained.
_________________
Karishma Veritas Prep  GMAT Instructor My Blog
Get started with Veritas Prep GMAT On Demand for $199
Veritas Prep Reviews



Senior Manager
Joined: 03 Apr 2013
Posts: 290
Location: India
Concentration: Marketing, Finance
GPA: 3

Re: A contractor estimated that his 10man crew could complete t [#permalink]
Show Tags
05 Dec 2017, 01:44
VeritasPrepKarishma wrote: ShashankDave wrote: Hi VeritasPrepKarishma, thank you for the prompt response. I understand your point. But considering what you have said, it would be needed to be specified by the question that if it rains for a portion of a day, the remaining time is used by the workers and that counts as a full day of work. Posted from my mobile deviceNo. The question tells you  "Assume the crew does not work on any rainy day " They worked partially on the last day because the work got over, not because it rained. Got it. Thanks a lot for your help. Also, is this an official question? what's the source? because I have seen this question in my CAT prep material somewhere. Posted from my mobile device
_________________
Spread some love..Like = +1 Kudos




Re: A contractor estimated that his 10man crew could complete t
[#permalink]
05 Dec 2017, 01:44






