10. Twenty individuals went on a particular diet plan for one month and lost an average of 2.75 lbs., with a standard deviation of 3.35 (i.e., M= 2.75, s = 3.35). To test the hypothesis that the true mean weight has not changed (i.e., H₀: = 0), would you use the one sample t-test for mean or z-test for mean? Please provide the reason for your answer.