Bunuel wrote:
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?
A. 4
B. 5
C. 6
D. 7
E. 8
The answer for this question will be 5.
We know that 10 man can complete the work in 110 days, so total work done would be 1100. We know that no one works on days in which it rains. After 55 days the work completed would be 550.
So the remaining work = 1100-550= 550.
After 55th day, there was 5 day rain and from 61st day the workers increased from 10 to 16.
New number of workers = 16.
The question says the work was completed in 100 days after the 61st day.
Therefore, total number of days the 16 workers worked for including the rainy days = 40.
We are told work is completed in 100 days, and total work remaining was 550. Therefore they completed the work in 550/16=34.4 days.
Normally in 40 days the 16 workers should have completed 640 work. But only 550 was remaining hence the extra 90 work will be the days when they didn't work.
Therefore total number of days it rained after 61st day = 90/16 = 5.625 but since days cannot be in decimal we select 5 as if we select 6, the work will be completed in 34 days but the work was completed in more than 34 days, so we round down 5.625 to 5
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