## Thomas' Calculus 13th Edition

average=$\frac{1}{(ln 2)^2} \int_{ln 2}^{2 ln 2} \int_{ln 2}^{2 ln 2} \frac{1}{xy}dydx$ =$\frac{1}{(ln 2)^2} \int_{ln 2}^{2 ln 2}[\frac{ln y}{x}]^{2ln2}_{ln2}dx$ =$\frac{1}{(ln2)^2}\int_{ln 2}^{2 ln 2}\frac{1}{x}(ln 2+ln ln 2-ln ln 2)dx$ =$\frac{1}{ln2}\int_{ln 2}^{2 ln 2}dx$ =$\frac{1}{ln2}[lnx]^{2ln2}_{ln2}$ =$\frac{1}{ln2}(ln 2+ln ln 2-lnln2)$ =1