A certain chemical process is run 10 times at a temperature of 65—¦C and 10 times at a temperature of 80—¦C. The yield at each run was measured as a percent of a theoretical maximum. The data are presented in the following table.

a. For each temperature, estimate the mean yield and find the uncertainty in the estimate.
b. Estimate the difference between the mean yields at the two temperatures, and find the uncertainty in the estimate.

65CI 71.3 69.1 70.3 69.9 71.1 70.7 69.8 68.5 70.9 69.8 80C 90.3 90.8 91.2 90.7 89.0 89.7 91.3 91.2 89.7 91.1