A factory that employs 1000 assembly -in workers pays each of these workers at a rate of Tk. 5 per hour for the first 40 hours worked during a week and 1.5 times that rate for the hours worked in excess of 40 hours. whatis the total amount paid to the workers in a week in which 30% of the workers worked 20 hours, 50% worked 40 hours and the rest of the workers worked 50 hours?