Final answer:
The critical value for a two-tailed hypothesis test at a 5% significance level is usually 1.96, but the actual value may vary depending on the distribution, sample size, and the specifics of the test.
Step-by-step explanation:
The question pertains to statistics and specifically to hypothesis testing. In this scenario, a student is testing the hypothesis that the population mean of a rectangular room is not equal to 50. This is done using a sample mean of 48 and a sample standard deviation of 11. The question seems to be asking for the critical value at a 5% significance level but does not state whether it's a one-tailed or two-tailed test. Assuming it's a two-tailed test, the closest critical value for a 95% confidence interval (5% significance level) from a Z-table is typically 1.96. For other hypothesis testing scenarios, such as comparing two population means, determining if the population standard deviation is greater than a certain value, or testing a population proportion, different critical values and distributions might be used, such as t-distributions or Chi-square distributions, depending on the sample size and other parameters.