Problem Solving

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?

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imo:5

The project required 10*110 = 1,100 man-days

so whatever happens has to equal 1100 to complete the project

we are told that of the first 60 days there were 5 days of rain, so:

55*10 + 5*0 = 550 (half way there)

then we hire 6 people so up to 16 employees and work until day 100. Let's assume there is NO rain, then they would have:

40*16 = 640

but since the job only needed 550 to complete and we have 16 ppl on board then:

(640-550)/16 = 90/16 ~ 5.6 ish

so there must have been at least 5 days of rain though 6 is too much (they would have needed MORE time)... Perhaps they busied themselves by whistling at scantily-clad women for ~0.6 days

Hope that helps

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?