A normally distributed quality characteristic has specification limits at LSL = 50 and USL = 60. A

Question:

A normally distributed quality characteristic has specification limits at LSL = 50 and USL = 60. A random sample of size 35 results in x  55.5 and s  0.9.
(a) Calculate a point estimate of Cpk.
(b) Find a 95% confidence interval on Cpk.
(c) Is this a 6-sigma process?