Question

in an over-fished area, the catch of a certain type of fish is decreasing at an average rate of 8% per year. If this decline persists, how long will it take for the catch to reach half of the amount before the decline???

Answer 1

n = n0(1 - 0.08)^t 
= n0(0.92)^t 

Putting n = n0 / 2: 
1 / 2 = 0.92^t 
t = log(1 / 2) / log(0.92) 
= 8.31 yr.