rahul.s wrote:3 machines have a productivity ratio of 1:2:5. all 3 machines are working on a job for 3 hours. at the beginning of the 4th hour, the slowest machine breaks. it is fixed at the beginning at hour 7, and begins working again. the job is done in 9 hours. what was the ratio of the work performed by the fastest machine to the work performed by the slowest?

again, there are no answer options

OA: [spoiler]15:2[/spoiler]

3 machines have a productivity ratio of 1:2:5.
Let x be the production of slowest machine per hour. so productivion per hour of middle machine 2x and production of fastest machine 5x
so total production per hour = x+2x+5x =8x.

production by slowest machine in 3 hr + work done in the last 3 hrs = 6x
production by middle machine in 9 hr = 2x9 = 18x
production by fastest machine in 9 hr = 5x9 = 45x


so ration of work done by fastest machin to slowest = 45/6 = [spoiler]15/2 Ans[/spoiler]

See atlast you need to find
the ratio of work performed by fastest mach. to slowest mach. = Ratio of Productivity of Fastest to slowest mach.
= (5*9x)/(1*6x) [9 hrs work by fastest mach.and 6 hrs work by slowest mach. ]
= 15/2