Six Sigma;
The breaking strength of a fiber is required to be at least 150 psi. Past experience has indicated that the standard deviation of breaking strength is sigma = 3 psi. A random sample of four specimens is tested. The results are y1=145, y2=153, y3=150 and y4=147.
a. State the hypotheses that you think should be tested in this experiment.
b. Test these hypotheses using α= 0.05 . What are your conclusions?
c. Construct a 95 percent confidence interval on the mean breaking strength.
![1843_Equation.jpg](https://secure.tutorsglobe.com/CMSImages/1843_Equation.jpg)