Solve for the unknown number of years in each of the following:

Note: Do not round intermediate calculations and round your answers to $2$ decimal places, e$.$g$.,32\mathrm{.}16.$

$\backslash$table$[[$Present Value,Years,Interest Rate,,Future Value$],[700,,8,\%,1,555],[2,391,,6,\%,4,150],[33,705,,11,\%,391,620],[33,400,,18,\%,211,820]]$