[填空题]
A population of goldfish deb*l9xg.djte6 f es )7jcreases expohlh z/ 0e6y2rtnentially. The size of the population, P , after t days is modelled by h6 zrhe ty20/lthe function
$P(t)=8000 \times 2^{-t}+100, \quad t \geq 0 \text {. }$
1. Write down the exact size of the initial population.
2. Find the size of the population after 5 days.
3. Calculate the time it will take for the size of the population to decrease to 120 .
The population will stabilize when it reaches a size of n .
4. Write down the value of n .
