1. The problem statement, all variables and given/known data For this question , i am not sure how to get the Q , Can i use the middle part instead of the right part ? 2. Relevant equations 3. The attempt at a solution if i use middle part , my ans would be (0.35)(0.025)(0.18676-0.175) = 1.03x10^-4 , which is different from the ans . Is it wrong ? If it's wrong , why cant i take the middle section ( green part) ?