In exercises that call for two-sample procedures, you may use either of the two approximations for the degrees of freedom that we have discussed: the value given by your software or the smaller of and . Be sure to state clearly which approximation you have used.
7.47 Understanding concepts.
For each of the following, answer the question and give a short explanation of your reasoning.
7.47
(a) Because 0 is not in the interval, we can reject the null hypothesis; the data support a significant difference between the two means. (b) Generally, a larger sample will result in a smaller margin of error.