A stock paid the following dividend payments over the last four years $($from oldest to most recent$)$: $$4\mathrm{.}14,$ $$4\mathrm{.}55,$ $$4\mathrm{.}72,$ $$4\mathrm{.}60.$ It recently paid a dividend of $$5\mathrm{.}00$ and the current stock price is $$90\mathrm{.}20.$ Calculate the cost of equity by estimating the geometric average growth rate.