The current population of a threatened animal species is 15

The current population of a threatened animal species is 1.5 million, but it its declining with a half-life of 25 years. How many animals will be left in 40 years? in 80 years? The population after 40 years will be animals.

Solution

new value = (initial value ) *(1/2)^(t/ t1/2)

= 1.5 * (1/2) ^(40/25)

= 0.494 million

after 80 years it will be

1.5 * (1/2) ^(80/25)

=0.163 million