The construction work is assigned to the Group-I of 7 workers. They complete the task in 12 days. Another Group-II started the same task with same number of workers. They started the work and just after 5th day their 2 workers left the work. Now, in how many days this Group will complete the task?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 9.8 Days
The total work is measured in worker-days (one worker working for one day). Group-II does the same task, so it needs the same number of worker-days as Group-I.
Total work: \(7\times12=84\) worker-days
Work done in the first 5 days by all 7 workers: \(7\times5=35\) worker-days
Work left: \(84-35=49\) worker-days, now done by \(7-2=5\) workers
Days needed: \(\displaystyle\frac{49}{5}=9.8\) days
The options count the days after the two workers left; the whole task takes Group-II \(5+9.8=14.8\) days.