a machine being used by a company is estimated to have a life of 15 years. at that time a new machine would cost 75000 and the scrap of the old machine would yield 9600 only. a sinking fund is created for replacing the machine at the end of its life. what sum should be per annum? retained by the company at the end of every year to accumulate at 6% the end of each year in a sinking fund so that at the​ end of every year to accumulate at 6% per annum.​