Solve for the unknown number of years in each of the following: $($Do not round intermediate calculations and round your answer to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$

$\backslash$table$[[$Present Value,Years,Interest Rate,Future Value$],[$$$,195,8,\%,$$$,873],[$$$,2,105,,11,,$$$,3,500],[$$$,47,800,,10,,$$$,326,500],[$$$,38,650,,15,,$$$,213,380]]$