2-1 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 V = 3 psi. A random sample of four specimens...

2-1 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 V = 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 D = 0.05. What are your conclusions? (c) Find the P-value for the test in part (b). (d) Construct a 95 percent confidence interval on the mean breaking strength.