I am drawing a blank on how I find Sd. Can someone help me explain it to me. Thank you!

Listed below are body temperatures from five different subjects measured at 8 AM and again at 12 AM. Find the values of d and so. In general, what does Ha represent? Temperature ( F) at 8 AM 97.7 98.6 97.6 97.1 97.7 Temperature ( F) at 12 AM 98.6 99.2 97.8 96.9 98.0 Let the temperature at 8 AM be the first sample, and the temperature at 12 AM be the second sample. Find the values of d and sa. d = -.360 (Type an integer or a decimal. Do not round.) So = 0.42 (Round to two decimal places as needed.) In general, what does u represent