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)...

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 x = 86

why this choice of alternative hypothesis is better than H1: µ <>

(b) A random sample of 20 welds results in psi and s x = 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.