10 machines work at constant rate and working together, they complete a job in 16 hrs. How mny hrs needed if only 8 machines work together to complete a job?
My take is B (20). The explaination as follows.
The way I understand this type of problems is by translating the problem into a ratio. In this problem as the number of machine increases, the number of hours required decreases and vice a versa. So the ratio has to be inversly proportional as follows
10/8 = x/16
So 8x = 160
and x = 20
I hope this makes sense.