Elsa has a portfolio consisting of the following:

$400$ shares of preferred stock with annual dividends of $$0\mathrm{.}26$

$15-$year $$2500$ zero$-$coupon bond

Find the Macaulay duration of Elsa's portfolio at $5\%.$ Round your answer to three places after the decimal.

$(0\mathrm{.}05,\backslash$infty $)$ years