Question

150 workers were engaged to finish a piece of work in a certain number of day. four worker added on the second day, four more workers added on third day and so on. it takes 8 less days to finish the work now. find the number of days in which the work was completed

Answer 1

Let the work has been completed in n days
total no. of workers = 150+146+142....
n/2 (150×2+(n-1)4)
total no. of workers = 150 (n-8)
n(150+2n-2)= 150 (n-8)
150n+2n×n-2n= 150n -150×8
n×n-n+600
n= 25