Now that we are in the digital age, younger people have little idea about standard printed photo dimensions, but the most common US size before their demise in popular culture was the 4x6 inch print size, which in Europe was very close to the 10x15 centimeter size. This closeness means we can compare the areas of the two sizes usig the differential approximation for the calculated area.
In the USA (inch units), the 4x6 photo prints have dimensions 4 in by 6 in. In Europe (cm units) the 10x15 prints have dimensions 10cm by 15 cm. Unit conversion: 1 inch = 2.54 cm. Use the differential approximation to estimate the absolute change and percentage change in the (computed) area of the USA format (new) compared to the European format (old): A = x y . Then compare your linear estimates for both to the corresponding exact changes. [HINT: apply the differential approximation using the x and y values of the European format, with the differentials dx and dy given by the differences USA format dimensions minus the European dimensions.] [Solution: 4x6prints.mw]