work problem !! plzz help !!!

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charmaine: Senior | Next Rank: 100 Posts; Posts: 71; Joined: Sun May 18, 2008 11:04 pm; Thanked: 1 times

work problem !! plzz help !!!

by charmaine » Wed Jun 25, 2008 4:03 pm

working independantly, Sophia can finish a certain job in hald the time Monica can. If sophia works alone at the job for 5 days and then Monica work 6 days to finish the remaining job. how many days will it take Sophia to finish the whole job ?

answer is 6

i dun get why ?????

thanks thanks

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Source: Beat The GMAT — Problem Solving | Wed Jun 25, 2008 4:03 pm

GMAT/MBA Expert

Ian Stewart: GMAT Instructor; Posts: 2623; Joined: Mon Jun 02, 2008 3:17 am; Location: Montreal; Thanked: 1090 times; Followed by:355 members; GMAT Score:780

Re: work problem !! plzz help !!!

by Ian Stewart » Wed Jun 25, 2008 4:25 pm

charmaine wrote:working independantly, Sophia can finish a certain job in hald the time Monica can. If sophia works alone at the job for 5 days and then Monica work 6 days to finish the remaining job. how many days will it take Sophia to finish the whole job ?

answer is 6

i dun get why ?????

thanks thanks

Are you sure the answer is 6?

Sophia needs half as much time as Monica needs to do the same amount of work. We know that 5 days of Sophia's work plus 6 days of Monica's work finishes the job. Well, Sophia could have done Monica's share of the job in half the time: 3 days. It should therefore take Sophia 5+3 = 8 days to finish the job.

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