control alarm

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control alarm

by YellowSapphire » Fri Oct 01, 2010 7:38 pm
Source: Veritas Prep CR2

76. A control alarm on the multi-line NXD-10 goes off when its separate production lines change widget-manufacturing speeds at different rates. Due to bottleneck constraints, the widgets are damaged if, on average, the NXD-10 produces widgets faster than 110% of its normal rate. In order to track quality control, company policy requires that all differential speed changes be reported by NXD-10 operators to upper management. Since every reported differential speed change reduces employee bonuses, NXD-10 operators in practice only report differential changes that will be discovered later, i.e. due to damaged products.

If the statements above are true, which of the following describes a situation in which an NXD-10 control alarm would go off, but the incident would not be reported to upper management?

A: Gauges show a sharp and uniform increase in widget production.
B: Gauges show an overall increase in widget production to twice the normal rate-with some lines increasing production rapidly, others slowly.
C: Gauges show that widget production has risen sharply to 120% of the normal rate; yet one NXD-10 line had a slower production rate than it did previously.
D: Gauges show that widget production has for the most part dropped at a constant rate; yet one NXD-10 line sped up slightly.
E: Gauges show a significant and uniform decrease in widget production.
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by psychomath » Sat Oct 02, 2010 9:24 am
I think I ll go with D....

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by abhi.genx7 » Sat Oct 02, 2010 10:37 pm
Really need a solid expert explanation for this , some tough question this is !!!

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by ov25 » Sun Oct 03, 2010 10:58 am
D makes sense....

3 ways to detect speed changes 1) speed > 120, 2) more production and 3) damaged widgets

1) Management should not find it, except with damaged widgets, when speed changes....

slight increases...might slip through...because even though alarm goes off, the the production quantities might just balance between the fast/slow lines..D

Whereas in C, an abrupt change as 120% might be difficult to compensate with slower lines, so mgmt might detect using production quantities rather than waiting when inspecting the damaged pieces...

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by David@VeritasPrep » Sun Oct 03, 2010 7:08 pm
OA is D.

This is an interesting question and one that often needs some explanation.

First let me say that this is as difficult as anything that you would see on the test...For a tough question like this slow down and go back to the basics and try to break this into manageable pieces - like a quant problem.

Now you are looking for the answer choice that is a scenario in which the alarm would go off and this would not be reported to management. We are told that the alarms are only reported to management if there is some evidence of the problem - specifically if there are damaged products.

First let's see when the alarm will go off and let's eliminate the choices that do not satisfy this criteria.

In order for the alarm to go off, the separate production lines need to change manufacturing speeds at different rates. We can eliminate choices A and E due to the fact that in both of these choices the increased or decreased speed is uniform, so the alarm would not go off.

In the other three choices the lines change speed at different rates so the alarm would go off. Now we need to look for the circumstance where the management would not know of this and therefore the employees would keep their bonuses by not telling!

Well, we need to not have any damage to the products (as stated in the stimulus). So how are products damaged? By producing widgets at over 110% of the normal rate. So we want a scenario where this does not happen. Answer Choice B involves widget production at twice the normal rate so this would damage the products and is eliminated. Answer Choice C has widget production at 120% so this is over 110% and also would result in damage.

Answer D is the correct answer since most production dropped and one line increased slightly, meaning that production would not be over 110% - so no damage.

Hope that helps to untangle this nest....
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by YellowSapphire » Tue Oct 05, 2010 8:15 am
Thanks David for wonderful explanation.
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by David@VeritasPrep » Tue Oct 05, 2010 10:43 am
YellowSapphire -

You are welcome. I enjoy working with critical reasoning- it just makes so much sense sometimes. Check back at the end of the week I will be posting some new original questions that I have just written. I look forward to seeing if people get them right!

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