Final answer:
The degrees of freedom for the given t tests are 11 and 29 respectively.
Step-by-step explanation:
The degrees of freedom for a one-sample t test is df = n - 1, so in this case, the degrees of freedom would be 12 - 1 = 11. For a two-independent-sample t test, the degrees of freedom would be df = n1 + n2 - 2, so in this case, it would be 12 + 19 - 2 = 29. The critical value 63.657 and significance level α = .01 indicate a two-tailed test, so the degrees of freedom would be the same as the number of observations in the data.