Answer:
initial population : 89
after 9 years : 676
Explanation:
no need for panic. this is just plain calculator mechanics. yes, we need to do some more complicated typing and use e, but it is still only typing.
the initial population is P(0). or t = 0.
simply when there were 0 years since the fish were added.
that is simple.
we get (as -0.42×0 = 0)
800 / (1 + 8e⁰) = 800 / (1+8×1) = 800 / 9 ≈ 89
now, after 9 years we have to calculate P(9). or t=9.
let's pre-calculate : -0.42×9 = -3.78
e to the power of -3.78 = 0.022822691...
8 times this is 0.182581531...
and plus 1 is 1.182581531...
800 / 1.182581531... = 676.486127 ≈ 676