Question

The normal scrap loss for four successive operations is 5%, 3%, 15% and 10% respectively. How many units should be started through in order to finish with 1,200 pieces? Find:

a) The total machine time needed if the operation times are 3, 6, 4, and 5 minutes, respectively.

b) The total cost if the cost per unit for each successive operation is $2, $5, $3, and $1, respectively.

Answer 1

operations	normal scrap loss	1-loss %
1	5%	95%
2	3%	97%
3	15%	85%
4	10%	90%
required output	1,200	pieces
Output Required=Input Given *(1-Loss1%)*(1-Loss2%)*(1-Loss3%)*(1-Loss4%)
1200 = input *(1-0.05)*(1-0.03)*(1-0.15)*(1-0.10)
solve for input:
input = 1200/(95%*97%*85%*90%)
input	1702	pieces
	(rounding off)
a)
operations	time/unit (min)	time
1	3	5107
2	6	9703
3	4	6275
4	5	6667
	total time	27751
		min
b)
operations	cost/unit	cost
1	$              2	$    3,404.51
2	$              5	$    8,085.71
3	$              3	$    4,705.88
4	$              1	$    1,333.33
	total cost	$ 17,529.43

formulae used: