Question: Physical Sciences A pressure-relief valve (PRV) is installed on a residential hot-water heater to protect against overheating and, of course, high pressure. Independent random samples of PRVs from different companies were obtained. Each value was tested by recording the pressure (in psi) required to cause the valve to open. The summary statistics are given in the following table.
Assume the underlying populations are normal, with unequal variances.
a. Is there any evidence to suggest that the mean pressure required to open each valve is different? Use a = 0.05.
b. Find a 95% confidence interval for the difference in population mean pressure required to open each valve. Is this confidence interval consistent with the results in part (a)? Explain.