Question 1193272
The population of bison was almost hunted to extinction when the United States
expanded westward.
 The population decreased by 40% per year when the expansion began in 1803.
 If the herds of bison originally contained 500,000 bison, long would it
take for there to only be 1,000 bison left? 
:
let t = time required for this to happen
With 40% decrease, that means .6 of original amt remain
:
500000*.6^t = 1000
.6^t = 1000/500000
.6^t = 1/500
uing natural logs
t*ln(.6) = ln(1/500)
t = ln(1/500)/ln(.6)
using calc
t ~ 12 years