The cooling system in a nuclear submarine consists of an assembly of welded pipes through which a coolant is circulated. Specifications require that weld strength must meet or exceed 150 psi.
(a) Suppose that the design engineers decide to test the hypothesis H0: μ = 150 versus H1: μ > 150. Explain why this choice of alternative hypothesis is better than H1: μ < 150.
(b) A random sample of 20 welds results in = 153.7psi and s = 11.3 psi. What conclusions can you draw about the hypothesis in part (a)? State any necessary assumptions about the underlying distribution of the data.