a. A statistics practitioner randomly sampled 1,500 observations and found x = 14 and s = 25. Test to determine whether there is enough evidence at the 5% significance level to infer that the...

a. A statistics practitioner randomly sampled 1,500 observations and found x = 14 and s = 25. Test to determine whether there is enough evidence at the 5% significance level to infer that the population mean is less than 15. b. Repeat part (a) assuming that you know that the population standard deviation is σ = 25. c. Explain why the conclusions produced in parts (a) and (b) are virtually identical.