Any Six Sigma black belts to support

[Georgi]

Hi all,

New to the forum. I recently took on the 6 sigma journey and study online but got stuck a bit with some questions for my green belt exams. I hope someone here could help.

Can someone demonstrate help how to get to the right answer?

A production line is used for producing chocolate bars. However, it has experienced 3 breakdowns in the last 6 weeks, and the manager is concerned that customer demand has now ''out-stripped'' the production lines' capacity.

Assess the production line to determine if the current process is able to meet customers' demands. The organisation expects all its lines' CP to be between 1.3 and 1.8.

The information that you have been provided states that the customer is happy to accept chocolate bars with a weight of 220 grams +/-5 grams tolerance. The production line averages 2000 chocolate bars a day with an SD of 60 bars. The manager has set a daily production target of 1600 to 2200 bars per day (inventory dependant).

Takt time is 3.7, and the first-time yield is 96%.

Using the information above what is the current CP ( to the nearest two decimal points)

• 1.55
• 1.76
• 1.67
• 0.66
• 1.00

Thanks

 

[Miner]

This problem contains a lot of information, most of which is irrelevant to the question. Ask yourself what the real question is. To what does the capability (Cp) apply (weight, daily production, takt time)? Once you determine that, cross out all information that is irrelevant. This will simplify the problem and it should become clear.

 

[Mike S.]

Six sigma

Some MBB calculating CP's instead of looking at the voice of the process.

 

[Bev D]

Well the OP is asking for help with a poorly worded question and Miner gave them some useful advice with their question.

Of course the question is poorly worded for no purpose except to torture the OP as it’s core question regarding CP is useless - it is just a vehicle to have the OP practice some math (and it’s just basic division). It provides no insight let alone any direction that is actionable to the process.

The original six sigma (before it got that cute name) was useful and focused on making real improvements to quality. Cue the hack consultants and ‘six sigma’ became a useless exercise in even more useless math that lacked any useful context. You would have been better off taking a theoretical statistical class…and saved a ton of money.

 

[Semoi]

The Cp value is related to the first pass yield. Thus, what you ought to do is
1. assume (!) a normal distribution and
2. assume (!) that it is entered between the specification limits.
Using these two assumptions you can calculate the distance between the lower specification limit and the center of the normal distribution (in units of the standard deviation).
Finally, you apply the Cp formula.

If I perform these steps, I get 0.684583. Thus, the mathematically correct answer would be that all given solutions are wrong (to the nearest two decimal points). However, if you look at the options, there is an obvious expected answer