1. Data Outer Diameter of tube=(64 +/- 2) and internal diameter= (47 +/- 1). Find cross-sectional area of tube and find percentage uncertainty. 2. Equations 3. The attempt at a solution I got (Delta A)/A = (Delta D2-d2)/(D2-d2) where D2-d2=1887 +/- 198. Hence my A= 1500 and my delta A is 157. But the correct answer is 1500 +/- 300. And percentage uncertainty is 20%. Can anyone give me the equations of the uncertainties??? For example there is another question about z=2x2 + y. Can you give me the equation? Im still very blur about this topic.