Ending Amount = Beginning Amount / 2^n
where "n" is the number of half-lives (time / half-life)
Ending Amount = 1.0 / 2^n
2^n = 1.0 / .95
2^(time / half-life) =
1.0526315789
elapsed time = half-life* (log (bgng amt / end amt) / log(2)
elapsed time = 1,760 * log (1.0526315789) / 0.30102999566
elapsed time = 1,760 * 0.022276394692 / 0.30102999566
elapsed time = 130.2410232308
years
