## Friday, November 26, 2010

### CP

A contractor estimated that his 10-man 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 61-st 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?
(C) 2008 GMAT Club - [t]m07#6[/t]
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• The amount of work in man-hours is: $110 * 10 = 1100$ mh. After 60 days with 5 days of rain (55 net days) the crew of 10 had completed 550 mh of work, and had 550 mh more to go. Of the remaining 40 days, $x$ were raining. The last 550 mh were completed by 16 men: $(40 - x) * 16 = 550$ , and $x = 5.625$ . 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.