From the following particulars, work out the earnings for the week of a worker under

(a) Straight piece rate

(b) Differential piece rate

(c) Halsey premium system

(d) Rowan system Number of working hours per week = 48 Wage per hour = Rs. 3.75 Normal time per piece = 20 minutes Rate per piece = Rs. 1.50 Normal output per week = 120 pieces Actual output for the week = 150 pieces Differential piece rate: 80% of piece rate when the output is below standard and 120% when above standard.