time taken per cycle = sum of all activities = 13 min.
Case 1 – When the operator does not take any rest,
no. of cycles completed in 8 hours = 480 /13 = 36.92
Units produced in 36.92 cycles = 73.84 =73 [ It is assumed that one unit per machine per cycle is produced]
Cost per 8 hrs. = 15×8 + 30x2x8 = 600
Cost per unit = 600/73 =8.219
Case II – Now, the cycle time inclusive of rest time of 3 min per cycle = 13+3 =16
No.of cycles completed in 8 hrs = 480 /16 = 30
Units produced in 8 hrs = 30×2 =60
New cost per unit = 600/60 =10 per unit
Hence the cost increases per unit by (10-8.219) = 1.78