Unknown Time & Unknown Interest Rate
At a constant force of interest of 5%, a loan is being repaid with 3 payments: a payment of 1000 at the end of 10 years, a payment of 4000 at the end of 20 years, and a payment of 10000 at the end of 30 years.
Compute the time T the borrower could repay the loan with a single payment of 11500.
T=
(Give your answer correct to 2 decimal places)