10.42 Find the confidence coefficient, t df,



2

, that would be used to find the maximum error for each of the following situations when estimating the difference between two means, 1  2.

a. 1    0.95, n1  25, n2  15

b. 1    0.98, n1  43, n2  32

c. 1    0.99, n1  19, n2  45