Question

Circle the best answer. The choice between a z-test and a t-test for a population mean depends primarily on: a. the sample size. b. the level of significance. c. whether a one- or two-tailed test is indicated. d. whether the given standard deviation is from the population or the sample. e. a z-test should never be used. 3

Answer 1

a)The sample size

Explanation:

t - student distribution should be used whe we are facing a Normal Distribution population andwhen a sample size n is below 30.

t- student distribution is also a associated to a bell shape but is more flat and the values are more spread, tails are much more wide.

t- student use the concept of degree of fredom ( each degree of fredom correspont to an specific curve). As degree of fredom increase the curves become more close to a bell shape. For n = 30 t-student curve is a bell shape one