The compressive strength od steel beams is normally distributed. A random sample of 6 steel beams has a mean compressive strength of 58,392 psi (pounds per square inch) with a standard deviation of 648 psi.

(a) At the 0.05 level of significance, is there a significant evidence that the standard deviation of the compressive strength for the given kind of steel is greater than 600 psi?

(b) Find the 95% lower confidence limit on , LCL=square root of( (n1)s^2/ 2 0.05,n1) . Show that "YES"in (a) coincides with "600 LCL"and "NO"in (a) coincides with "600 > LCL".