Case 1:
A sample of 49 measurements of tensile strength for
roof hangers are calculated to have a mean of 2.45
and a standard deviation of 0.25. (Units are Newton's
per square meter.)
a. Determine the 95% confidence interval for mean
tensile strength for all hangers.
b. Interpret this confidence interval.
Case 2:
The contents of seven similar containers of sulfuric
acid are 9.8, 10.2, 10.4, 9.8, 10.0, 10.2, 9.6 liters.
Find a 95% confidence interval for the mean contents
of all such containers, assuming an approximately
normal distribution.
The sample mean and standard deviation for the given
data are x = 10.0 and s = 0.283 and t0.025 = 2.447.