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$],[$$$,610,7,\%,$$$,1,389],[$$$,940,,8,8,\%,$$$,1,821],[$$$,26,350,,9,\%,$$$,289,715],[$$$,43,500,,11,\%,$$$,430,258]]$