1. The problem statement, all variables and given/known data http://www.geocities.com/asdfasdf23135/stat15.JPG I am OK with part a, but I am having some troubles with part b. 2. Relevant equations Width of a Confidence Interval 3. The attempt at a solution Attempt for part b: http://www.geocities.com/asdfasdf23135/stat16.JPG note: P(T>t_(n1+n2-2),alpha/2)=alpha/2 where T~t distribution with n1+n2-2 degrees of freedom. Now, as n1 increases and n2 increases, (i) t_(n1+n2-2),alpha/2 gets smaller (ii) denominator gets larger (iii) the ∑ terms gets larger because the upper indices of summation are n1 and n2, respectively (i) and (ii) push towards a narrower confidence interval, but (iii) pushes towards a wider confidence interval. How can we determine the ultimate result? Any help is greatly appreciated!