I am learning about linear interpolation however, we were not taught how to formally solve a problem using linear interpolation. A practice problem involving is the following:
Find how long it will take for a certain sum of money to double itself at compound annual interest of 20%. Solve this problem. Then solve this problem by first finding $(1.2)^3$ and $(1.2)^4$ and then by linear interpolation, approximating $x$ such that $(1.2)^x=2$. Show the result so obtained is equal to the Mesopotamian solution expressed sexagesimally as 3;47,13,20.