+128577 Here's (14)
.002 = e^(-.00012* t) take the ln of both sides
ln .002 = ln e^(-.0002 * t) and we can write
ln.002 = (-.00012 * t) ln e and ln e = 1, so we can ignore this......so we have
ln .002 = -.00012 * t divide both sides by -.00012
t = ln .002 / -.00012 = about 51,788 years old
+128577 Here's (15)
199200 = 80000(1 + r)5 divide both sides by 80000
2.49 = (1 + r)5 take the log of both sides
log 2.49 = log (1 + r)5 and we can write
log 2.49 = 5 log ( 1 + r) divide both sides by 5
log2.49/5 = log (1 + r)
.079 = log(1 + r) and in exponential form ,we have
10.079 = 1 + r
r = 10.079 - 1 = .20 = about 20% per year
+128577 Here's (14)
.002 = e^(-.00012* t) take the ln of both sides
ln .002 = ln e^(-.0002 * t) and we can write
ln.002 = (-.00012 * t) ln e and ln e = 1, so we can ignore this......so we have
ln .002 = -.00012 * t divide both sides by -.00012
t = ln .002 / -.00012 = about 51,788 years old
