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work problem

by mehrasa » Mon Sep 05, 2011 9:21 am
Andy, George and Sally work on a project and they need to finish the job in 8 hrs. do the finish on time?
1) sally can finish in 4K+7 hr 1<k<5
2) Andy in 3+2k and george in 2k+1 hours

Solution: stat1: Not sufficient bcuz we need to know Andy and George rate as well
stat2: sufficient
if k=5 --> Andy finish in 13 hrs and George in 11 hrs => 1/11 +1/13 = 24/143 which is larger than 1/8 then both Geaorge and Andy finish the job without even help of sally ==> sufficient


HOWEVER, as I undrestood DS Qs is about determining whether these statements reach us to the answer not solving the problems mathematically... under this circumstance, the statement 2 also seems insufficient and it is most likely to choose C... i am confused...what do u think?
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by gmatclubmember » Mon Sep 05, 2011 9:55 am
Statement 1 and 2 together taken can solve the q.
Condition from 1, 1<k<5 can be used to in Stmt.2 to reach the answer.

So I would go with C. (Both statements needed).


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by knight247 » Mon Sep 05, 2011 2:17 pm
@Mehrasa,
My friend it looks like you have not mentioned 1<k<5 for the second statement

Let me mention the actual question

Andy, George and Sally are a team of consultants working on Project Alpha. They have an eight hour deadline to complete the project. The team members work at constant rates throughout the eight hour period. If the team of three has to begin work now and no one else can work on this project, will Project Alpha be completed by the deadline?

1.Sally can finish the project alone in 4k + 7 hours, where k is a positive integer with a minimum value of 1 and a maximum value of 5.
2.Working alone, George will take 2k + 1 hours and Andy will take 3 + 2k hours, where k is a positive integer with a minimum value of 1 and a maximum value of 5

Statement 1 as you said is insufficient as we don't have any info about the rates of the other ppl.

From Statement two, Lets assume that a total of 143 pages need to be typed in 8 hrs. For andy and george, Lets assume that k=5 so Andy finishes 143 pages by himself in 13 hrs and George finishes 143 pages by himself in 11 hours.

Andy's Rate=143/13=11 pages/hr So in 8 hrs he will finish 88 pages
George's Rate=143/11=13 pages/hr so in 8 hrs he will finish 104 pages. So in 8 hrs if Andy and George alone can finish 192 pages, with Sally's help they'd we able to finish even more in 8 hrs over exceeding the target of 143 pages. Hence SUFFICIENT.

Answer is B
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