Question

Ali and Ahmad are two managers at ABC corporation working in a shop with processes

V, W, X, Y, Z. These processes are somewhat similar and can be arranged in any manner.

Ahmad thinks the best arrangement is V, W, X, Y, Z while Ali thinks it is best to reverse

the arrangement and make it Z, Y, X, W, V.

If you know that each process has a scrap rate as follows:

V: 5%

W: 4%

X: 2%

Y: 5%

Z: 15%

And if you know that each process only work on good output from the previous process.

Which suggestion is better Ahmad’s or Ali’s?

Does the arrangement matter? And if yes, then How does it matter?

Please answer based on your full understanding of CH 6 and CH 7

Answer 1

Product yield (Y) or output is given by following formula:

Y = (total input)(% good units) = (total input)( 1 - % scrape rate)

Let’s determine the process output if the input is 100 for arrangements of process according to Ahmed’s suggestion:

Process	scrap rate	Yield of the process
Input		100
V	0.05	100*(1 – 0.05) = 95.0
W	0.04	95.0*(1-0.04) = 91.2
X	0.02	89.4
Y	0.05	84.9
Z	0.15	72.2

For the suggestion of Ahmed, the yield for 100 units from the system is 72.2 units

Let’s determine the process output if the input is 100 for arrangements of process according to Ali’s suggestion:

Process	scrap rate	Yeild of the process
Input		100
Z	0.15	85.0
Y	0.05	80.8
X	0.02	79.1
W	0.04	76.0
V	0.05	72.2

For the suggestion of Ali, the yield for 100 units from the system is 72.2 units

Since there is no difference in system yield for the different suggestion of arrangement of the processes, thus the arrangement of process does not change the yield level of the process.