Hi all,
I am at the end of my 1st assignment and i am really struggling with the final question, i have contacted my tutor and i am, currently waiting for a response via email.
I don't know if i am overthinking the question but i am unsure if i am working it out wrong or using the right process. None of the tutorial videos cover this question and there is 1 worked example in the back of the workbook which i have tried to follow but i am not convinced this is correct.
is anyone else struggling with this? or is anyone able to point me in the right direction please?
I HAVE POSTED THE QUESTION BELOW
cheers
Your analysis shows that the mean capacitance of a batch of 500 of the capacitors you have selected is 46 μF,
with a standard deviation of 4 μF. Assuming the capacitors are normally distributed, determine the number of
capacitors likely to have values between 42 μF and 50 μF.
Note: Use the z-table given in Appendix A when answering part c.
d) The Quality Assurance Department is anxious to improve the nominal value of the capacitors to ensure more of
them fall within the rated tolerance band. The manufacturing process is adjusted in an attempt to bring about
this improvement. Following the adjustment, a further sample of 100 capacitors is taken in order to determine
if the adjustment has resulted in an improvement to the nominal value of the capacitors. Analysing this second
sample, it is noted that the mean value is now 46.5 μF, with a standard deviation of 2 μF.
By comparing these new results of the capacitor values following the manufacturing adjustment, with the
values obtained in part (c) recorded before the adjustment, show whether or not you agree with the
hypothesis that the adjustment to the manufacturing process has had a beneficial effect by making the
capacitor values closer to the desired manufactured nominal value of 47 μF.
Illustrate your answer with a hand drawn sketch of the normal distribution, with shaded regions representing
the results of your analysis, which you can show to the Quality Assurance Manager.