A study was done on the propagation of an ultrasonic stress wave through a substance. In particular, attenuation in fiber-glass-reinforced polyester composites was measured. A random sample is 2.6, 2.5, 2.2, 2.0, 2.1, 2.3, and 2.6.
A) Construct a 90% confidence interval for the true mean attenuation values.
B) Find the sample size required to estimate the true mean attenuation values to within + or - 0.05 using a 90% confidence interval.