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- This topic has 9 replies, 5 voices, and was last updated 14 years ago by John Moffat.
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- November 24, 2010 at 5:57 am #46186
How do you know when to apply the formula or use the tabular method?
November 24, 2010 at 5:00 pm #71328You can only use the doubling rule (which I think is what you mean by the tabular method) if you are making 2 or 4 or 8 or 16 etc.. units (or batches).
If it is any different (for example 50 units) then you cannot get this from doubling and you have no choice but to use the formula.If it is in the exam, then almost certainly it will not be possible using doubling and you will be expected to use the formula. If the examiner wants you to prove you know the doubling rule then she will make it clear.
November 24, 2010 at 6:56 pm #71329I have a question regarding learning curve. I have though solved it but one thing is bugging me in the answer provided. I would like you to help me understand the bit in C part of the question. Question 2 , Past papers Dec 2009.
Find the cost of 128th chair
Frame costs 51
Labour 1.29 hours (using curve formula) x 15 = $19.35
Leather : (here is the problem) in question they say chair requires 2 meters of leather and 1 metre is $10. so according to this cost of material should be 20 however in answer this is wht they have done 20 x 100/80= 25
I m confused with this bit. I d like you to resolve it for me. you might have to check the question urself though.
extract of question about leather ‘ leather costs 10 per meter and 2 meters are needed to complete the chair , although 20% of the leather is wasted in the upholstry process’November 24, 2010 at 8:11 pm #71330The reason is this:
Because 20% of leather is wasted, it means that for every 100 meters they buy, 20 meters is wasted and so only 80 meters are able to be used.
So….if we need to use 80 meters, then we actually need to buy 100 meters (because the other 20 are going to be wasted).
We need to use 2 meters for every chair, but we need to buy more (because 20% of what we buy will be wasted).
So we need to buy 2 x 100/80 = 2.5 meters.
(Check: if we buy 2.5 meters, we will waste 20% of 2.5 = 0.5 meters. This leaves us with 2.5 – 0.5 = 2 meters, which is what we need for the chair)
The cost of buying 2.5 meters (at $10 per meter) is 2.5 x 10 = $25
November 24, 2010 at 8:32 pm #71331i agree with ur explanation. it was so simple !! thanks
December 1, 2010 at 6:42 am #71332You are welcome.
December 9, 2010 at 11:18 am #71333Sir I was doing this one sum in the BPP Kit, this is regarding quotation, we have to quote prices for a buyer, in which
Case 1:
Buys the 1st unit
Case 2: we make the first two units and he buys the third
Now how do we calculate this third units cost… ?
they have not given the learning rate they have just given that 80% learning effect will take place as production increases, now my problem is I have totally forgotten how to use log and am scared about what I would do in this case to get my exponential value, is it likely that they will ask us to find the learning rate ( i mean the -.07400851<--Example)December 9, 2010 at 11:36 am #71334It is difficult to answer exactly without seeing the question, and you have not said which question it is.
However if they have told you that the learning effect is 80%, then that is another way of saying that the learning rate is 80%.
I think you might be asking if you can be asked to calculate b. If so, then the answer is yes (although in fact they usually give you the value of b). the formula for b is on the formula sheet and so if the learning rate is 80% then b = log 0.8 / log 2Provided you have a calculator with a log button, then this should not be a problem.
December 10, 2010 at 10:09 am #71335question no 35bpp kit the question asks to work back and calcute learning rate is it examinable if it is help how to do it
December 10, 2010 at 12:53 pm #71336Yes – it is examinable, and it is effectively the same as the example I gave above.
Every time you double production, the average time (and therefore cost) falls to a fixed percentage of what the average was before.
In this question, the amount subject to learning for 1 unit is $30. If we produce 4 then the average is $22.71 (52.71 – 30).
So, if the learning rate is x, then when we double once – to 2 units – the average will be 30x, and if we double again – to 4 units – the average will fall again to 30 x^2. So….30x^2 = 22.71, or x^2 = 22.71/30 = 0.757. So x = 0.87 or 87%
If you are still unsure then watch my lecture on this website.
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