The following data (in pounds), which were selected randomly from a normally distributed population of values, represent measurements of a machine part that is supposed to weigh, on average, 8.3 pounds.

see attached for question prompt

I have already gotten the solution (also attached but I'm confused about the "s" component of the equation and how to solve for it in general. is there a formula that I'm missing ?

Correct. The following data (in pounds), which were selected randomly from a normally distributed population of values, represent measurements of a machine part that is supposed to weigh, on average, 8.3 pounds. 8.1 8.4 8.3 8.2 8.5 8.6 8.4 8.3 8.4 8.2 8.8 8.2 8.2 8.3 8.1 8.3 8.4 8.5 8.5 8.7 Appendix A Statistical Tables Use these data and a = .01 to test the hypothesis that the parts average 8.3 pounds. (Round the sample mean to 2 decimal places. Round the value of s to 2 decimal places. Round your answer to 2 decimal places.) . . . A The value of the test statistic is t = _| and we fa" t reJECt the "u\" hypthe5'5 ' . Click if you would like to Show Work for this question: Open Show Work n =20 J? = 8.37 5= .19 df=20-l =19 a! .01 Ho: p = 8.3 11.: y at 8.3 For two-tail test, af2 = .005 critical toos,19 =.86l x-y _ 8.37 -s.3 = 1 as s g J5 JTO Obsa'ved t = 1.65