Use Table 7 of Appendix B to determine the values of t /2 that would be used

Use Table 7 of Appendix B to determine the values of t_α/2 that would be used in the construction of a confidence interval for a population mean for each of the following combinations of confidence coefficient and sample size:
a. Confidence coefficient .99, n = 18

b. Confidence coefficient .95, n = 10

c. Confidence coefficient .90, n = 15