Author 
Message 
Manager
Joined: 02 Aug 2007
Posts: 228
Schools: Life

A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
12 Feb 2009, 20:45
2
This post received KUDOS
7
This post was BOOKMARKED
This topic is locked. If you want to discuss this question please repost it in the respective forum. A contractor estimated that his 10men 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, after 5 days of rain, on the 61st day, he hired 6 more people to finish the project early. If the job was done in 100 days, on how many days after day 60 was it raining? (A) 4 (B) 5 (C) 6 (D) 7 (E) 8 Source: GMAT Club Tests  hardest GMAT questions



Director
Joined: 27 May 2008
Posts: 542

Re: A contractor estimated that his 10men crew [#permalink]
Show Tags
12 Feb 2009, 21:17
4
This post received KUDOS
xALIx wrote: A contractor estimated that his 10men 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, after 5 days of rain, on the 61st day, he hired 6 more people to finish the project early. If the job was done in 100 days, on how many days after day 60 was it raining?
* 4 * 5 * 6 * 7 * 8 Total mandays needed = 10 X 110 = 1100 Mandays worked before 61st day =(605)X10 = 550 Mandays worked after 61st day = 16 X (40x), where x is the number of days it rained after day 60. 1100 = 550 + 16(40x) 16x = 90 > x = 5.6.... number of days it rained after day 60 = 5 ... option B.



Senior Manager
Joined: 30 Nov 2008
Posts: 489
Schools: Fuqua

Re: A contractor estimated that his 10men crew [#permalink]
Show Tags
13 Feb 2009, 08:49
1
This post received KUDOS
10 persons take 110 days ==> 10 persons complete 1/110 th work in one day ==> 1 person can work 1/1100 th work per day.
After 5 days of rain, on 61st day means 1o people worked for 55 day in 60 days.
Work completed in 60 days is 55 * 10 / 1100 = 1/2 ==> half of the work is done in 60 days.
6 More people were added to the list. Now with 16 people how much time does it take?
16 /1100 * x = 1 /2 ==> Solving x = 34.37 approximately 35 days.
Of the 40 days remaining 16 people took 35 days to complete the rest of the work.
So there should be 5 days raining.
IMO B.



Director
Joined: 25 Oct 2008
Posts: 596
Location: Kolkata,India

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
18 Sep 2009, 04:48
The OE states: Quote: x=5.625 Round the number of rainy days down to 5 as with 6 rainy days the crew would have worked less than 550 mh and not have completed the job. Could somebody please explain this part in detail?I rounded it to 6 as this no. should have been in any other context..
_________________
http://gmatclub.com/forum/countdownbeginshasended8548340.html#p649902



Current Student
Joined: 17 Sep 2009
Posts: 102
WE 1: 5 hr

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
18 Sep 2009, 06:05
well, I solved the question a little bit differently but I think it can help you about the explanation, it took 34,37 days for 16 workers to finish the left over job without any rainy days. the whole job was completed in 100 days, the first 10 worker group worked for 60 days (55+5rainy), so total time spent with 16 workers was 40 (10060), so we are left with the days that people worked for 34,37 which we round up to 35 because even if they don't work the whole day they were able work in some part of that day so we understand it didn't rain that day, too. so the number of days it rained is 4035=5



Director
Joined: 25 Oct 2008
Posts: 596
Location: Kolkata,India

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
18 Sep 2009, 18:00
ya i was having trouble with the last part as i rounded it to 6..its pretty tricky..does it mean that if the 5.6 goes to 6 it means it rained for MORE days n' so the workers would take MORE than 100 days to complete?Thats the reason we are rounding down?
_________________
http://gmatclub.com/forum/countdownbeginshasended8548340.html#p649902



Manager
Joined: 22 Jul 2009
Posts: 191

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
30 Sep 2009, 13:13
4
This post received KUDOS
1
This post was BOOKMARKED
Here's the answer using a RTW chart. As the gmatclub explanation says, Round the number of rainy days down to 5 as with 6 rainy days the 16 men crew would have completed less than 1/2 of the job.
Attachments
SnapS.jpg [ 16.31 KiB  Viewed 10854 times ]
_________________
Please kudos if my post helps.



Manager
Joined: 26 Nov 2009
Posts: 164

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
14 Jan 2010, 07:37
4
This post received KUDOS
10 men ==> 110 days
1 men ==> 1100 days
till 60 days all 10 men worked for 55 days (5 days rain)
55*10==>550 days
reamining 550 days of work was done with 16 men
1 men ==> 550 days 16 men ==> 550/16 => 34.375 so 35 days
no of days rained after 61st day ==> 4035 = 5
so my ans is B



Intern
Joined: 02 Nov 2009
Posts: 21

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
14 Jan 2010, 07:59
10 persons take 110 days ==> 10 persons complete 1/110 th work in one day ==> 1 person can work 1/1100 th work per day.
After 5 days of rain, on 61st day>>>> 10 people worked for 55 day in 60 days.
Work completed in 60 days is 55 * 10 / 1100 = 1/2 total work
Now, we got 16 persons:
16 /1100 * x = 1 /2 ==> Solving x = 34.37 >>35 days
40 days 16 persons have worked, so 4035=5 raining days
B



Intern
Joined: 01 Aug 2009
Posts: 2

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
15 Jan 2010, 03:06
10 men can do a work in 110 days they worked for 55 days ( 605 days) so they worked for half of days required and hence completed half of the work. balance half was to be done by 16 men ( 10 + 6 new hires) 10 man can do in 55 days 16 man can do in X days.....(solving we get x = 34.37 ~ 35 days). 40 days  35 days = 5 days



Intern
Joined: 04 Feb 2009
Posts: 7

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
15 Jan 2010, 05:58
Hi,
If someone wants to avoid decimal/roundoff approach then try this alternative
Total work= 1100 mandays Work done after 60 days (including 5 rainydays)= 550 mandays
After addition on 6 men into the crew total work per day = 16 mandays therefore, from day 61100 total work (considering no rainy day in between)= 40*16=640 mandays. No. of man hours lost due to rain between day 61100= 640550=90 mandays So, no. of rainy days between day 61100=90/16= 5 days
Answer (B)
 Jay



Manager
Joined: 23 Oct 2010
Posts: 84
Location: India

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
19 Jan 2011, 06:56
B.
total work required for one person to complete the job= 110 * 10 = 1100 61st day .. 5 days of rain.. hence work done in number of days = 605 = 55 d half of the work remians... = 550 d of work for one person if 10 + 6 people are deployed to complete work then => 550/16 = 34.4 d we will consider this as 35 d as full day of work is counted even if you spent an hour working on the last day.
100  ( 55 + 5d of rain + 35 d of work) = 100  95 = 5 d of rain



Manager
Joined: 26 Dec 2009
Posts: 136
Location: United Kingdom
Concentration: Strategy, Technology
WE: Consulting (Computer Software)

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
19 Jan 2011, 07:22
10 men completed work in 110 days. In 55 working days half of the work was done by 10 men. so, 1 man can do half of the work in 550 days. 16 men can do the same work in 550/16 days = 34.37 Total days to complete = 40 Rainy days = 4034.37 = 5.63 ~ 5 days.
B is the answer



Intern
Joined: 13 Jan 2011
Posts: 4

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
20 Jan 2011, 00:51
I explain: Call a man with a working day is Y Total working part to finish the construction : 10Y x 110 = 1100Y ( without rainny) According to the data above, It rains from 57th to 61st day5days. So, the working is 56x 10Y=560 Y And, the working requirement is 1100Y So that, the rest working requirement is 1.100 Y 560Y = 540 Y In the data, the construction finish with 100days. We have working day from 62 from 100days. That mean : 39 working day x 16Y=624Y The balance is 540 Y and 624Y : 84Y  a day with rain and no working with 16 man , 84Y : 16= 5.3 So, B is correct.



Senior Manager
Joined: 01 Nov 2010
Posts: 288
Location: India
Concentration: Technology, Marketing
GMAT Date: 08272012
GPA: 3.8
WE: Marketing (Manufacturing)

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
20 Jan 2011, 01:58
tejal777 wrote: The OE states: Quote: x=5.625 Round the number of rainy days down to 5 as with 6 rainy days the crew would have worked less than 550 mh and not have completed the job. Could somebody please explain this part in detail?I rounded it to 6 as this no. should have been in any other context.. i did the calculation and got the same result. it should rain for 5.625 day, which we can round off to 6(0.625 can be rounded to1). apart from this i didnt get the anyidea why OE gives such an explanation. if it rains for 6 day, then total men work will be = 16*34=544mendays work(which is less than required) but acc to problem it should be 550mendays work. the answer should be 5.
_________________
kudos me if you like my post.
Attitude determine everything. all the best and God bless you.



Intern
Joined: 19 Jun 2011
Posts: 38

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
23 Jan 2012, 11:14
powerka wrote: Here's the answer using a RTW chart.
As the gmatclub explanation says,
Round the number of rainy days down to 5 as with 6 rainy days the 16 men crew would have completed less than 1/2 of the job. Could you explain how you got 16/10 for the 2nd part of this table please. The chart does help out significantly in doing the problem I just don't understand that part nor the part where u got the equation below the chart. Also do you know where I can find a thread that discusses using a wrt table? In my Veritas Prep book they don't mention any tables for that equation just manipulating the equation to find the answers. Thanks!



Math Expert
Joined: 02 Sep 2009
Posts: 39638

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
23 Jan 2012, 19:43
2
This post received KUDOS
Expert's post
1
This post was BOOKMARKED
AzWildcat1 wrote: powerka wrote: Here's the answer using a RTW chart.
As the gmatclub explanation says,
Round the number of rainy days down to 5 as with 6 rainy days the 16 men crew would have completed less than 1/2 of the job. Could you explain how you got 16/10 for the 2nd part of this table please. The chart does help out significantly in doing the problem I just don't understand that part nor the part where u got the equation below the chart. Also do you know where I can find a thread that discusses using a wrt table? In my Veritas Prep book they don't mention any tables for that equation just manipulating the equation to find the answers. Thanks! Below approach might help to understand better the problem as well as the solution provided by powerka: 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 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. This question is also discussed here: acontractorestimatedthathis10man126158.htmlHope it helps.
_________________
New to the Math Forum? Please read this: 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



Intern
Joined: 19 Jun 2011
Posts: 38

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
23 Jan 2012, 23:46
Thanks Bunuel, that helped and made a lot more sense. I wish I could understand some of these harder problems more, it usually takes me a solid min or 90 seconds to sometimes comprehend and write out the equations or logic of the problems for these harder Q on the quant section



Intern
Joined: 10 Jan 2012
Posts: 27
Concentration: Strategy, Finance
GMAT Date: 10172013
WE: Consulting (Computer Software)

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
24 Jan 2012, 04:00
Hi My Solution is : Total Work = 10 x 110 = 1100 mendays Work competed = (Days 10 men work for) = 10 x 55 = 550 (no. of days are 55 because 5 days before 61st day are 55 days)Work remainig = 1100  550 = 550. Now, if 16 men work to complete this remaining work they will take = 550/16 = 34. 3 = ~ 35 Days. No of days actually taken = 100  61 + 1 (this is to calulate the numbers between 100 and 61) = 40 Total no days it rained = 40  35 = 5 [B]
_________________
Thanks & Regards Yodee
‘A good plan violently executed now is better than a perfect plan executed next week.’  General Georg S. Patton



Director
Joined: 14 Dec 2012
Posts: 832
Location: India
Concentration: General Management, Operations
GPA: 3.6

Re: A contractor estimated that his 10men crew (m07q06) [#permalink]
Show Tags
23 Jan 2013, 06:51
no. of men initially: 10 work to be done : 1 no. of days expected to finish using 10 men: 110 amount of work done in 1 day by 10 men :1/110 (1) hence it means 10 men complete 1 work in 110 days therefore 1 men will complete ds work in 1100 days(2) now 1100 days reqd to complete 1 work by 1 men therefore in 1 day amount of workdone by 1 man will be 1/1100 now till 60th day 5 days are lost so in 55 day work done by 10 men will be :55/110 using (1) and amount of work left :155/110=1/2 now we have 6 more men therefore in 1 day 16 men will complete 16/1100 work using (2) therefore no . of days more required to complete 1/2 work will be: (1/2)/(16/1100)= 35.625 days=35 days therefore no. of days it rained again=(10060)35=5 days no
_________________
When you want to succeed as bad as you want to breathe ...then you will be successfull....
GIVE VALUE TO OFFICIAL QUESTIONS...
GMAT RCs VOCABULARY LIST: http://gmatclub.com/forum/vocabularylistforgmatreadingcomprehension155228.html learn AWA writing techniques while watching video : http://www.gmatprepnow.com/module/gmatanalyticalwritingassessment : http://www.youtube.com/watch?v=APt9ITygGss




Re: A contractor estimated that his 10men crew (m07q06)
[#permalink]
23 Jan 2013, 06:51







