# A and B start working together on a project and both have the same efficiency in the beginning. However the efficiency of A decreases to 0.6 times the usual after working for 2 hours. If the project can be finished in 120 man hours, then find the minimum number of days required to finish the work if both do an equal manhours of work each day and the sum of the total number of hours of work by both each day is 12. [ Initial efficiency of A = Efficiency of B = 1 man hour].a)10 daysb)12 daysc)16 daysd)Cannot be determinedCorrect answer is option 'B'. Can you explain this answer? Related Test: CAT Quantitative Aptitude MCQ - 1

## CAT Question Rajgopal Hota Sep 05, 2019
Let the number of hours worked by B be x.
The hours worked by A = (12 - x)
The manhours of work finished by A = (12 - x - 2) x 0.6 + 2
(12 - x - 2) x 0.6 + 2 = x
x = 5
The total manhours o f work done by them in a day = 2*x = 2 x 5 = 10
Thus, the number of days required to finsih the work = 120/10 =12 days
Hence, option 2.