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project

by ketkoag » Fri Jun 19, 2009 5:02 pm
A can complete a project in 20 days and B can complete the same project in 30 days. If A and B start working on the project together and A quits 10 days before the project is completed, in how many days will te project be completed?
A. 18
B. 27
C.26.67
D.16
E.12

OA: 18 days
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by cramya » Fri Jun 19, 2009 5:09 pm
B has to work alone for 10 days

In 10 days B will complete 1/30 * 10 = 1/3 of work

So A and B must have worked to complete the remaining 2/3rd of the work

(1/20+1/30) * t = 2/3

t= 8


Total(T) = 10(1/3rd work completed by B) + 8(2/3RD WORK compelted by both A and B)

T = 18
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by nitya34 » Fri Jun 19, 2009 10:58 pm
taking cue from Cramya

step 1:::::last 10 days B alone will work

step 2:::::first few days A & B both work together at 12 days/work pace(1/20 + 1/30)


now step 1 does 1/3rd work

hence step 2 does 2/3 rd work in how many days?

(2/3) *(12)=8 days


total time = 10 + 8 =18 days
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by ketkoag » Mon Jun 22, 2009 3:36 am
ahh, was making a silly mistake.. u know guys even a simple problem might trouble sometimes!! :)
thanks guys..
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