The following observations were made on fracture toughness of the base plate of 18% nickel managing steel (in ksi vin, given in increasing order)].
69.5 71.9 72.6 73.1 73.3 73.5 75.5 75.7 76.0 76.1 76.2
76.2 77.0 77.9 78.1 79.6 79.6 79.9 80.1 82.2 83.7 94.5
a) Compute a 99% CI for the standard deviation of fracture toughness distribution. Is this interval valid whatever the nature of distribution?
b) Compute a 90% CI for the standard deviation of fracture toughness distribution.